The Spitter

The Spitter is a Special Infected that made her debut in Left 4 Dead 2.

The Spitter's mutations enable her to spit out a ball of mutated stomach acid which, upon hitting the ground, spreads out into a large pool. Any Survivors standing within the pool of acid take increasing amounts of damage based on how long they stand in it, this can be up to about 3 quarters of their heath with just one puddle. Overall the Spitter's acid does the most damage of any infected, but is also the least reliable as it only lasts for a short time, and once it pools out it is stationary and relatively easy to escape.

When killed, the Spitter leaves a smaller pool of acid around her corpse. She can sometimes be a bit difficult to hear, making somewhat faint squealing noises as opposed to the more distinct noises other Special Infected make, but the hacking noises she makes when she actually spits are easy to hear.

Extent of Mutations
Through mutation of the Infection the Spitter has developed the ability to project an extremely caustic acid from her mouth in a mortar-like fashion, projecting a concentrated ball of damage acid that explodes on contact and spreads into a large pool. This acid bomb has the ability to ignite gas cans and propane tanks and will likely be an advantage in Versus games. The Spitter's lower jaw, cheeks, nose and lips seem to be either gone or noticeably eroded, signs that she may not be entirely resistant to the acid she is coughing up. Her proportions are awkward and stretched, including the elongated neck and bloated belly, which are most likely used to accommodate and produce the fluids, and her big toe has shifted to the side of her right foot like the thumb of a hand. While running, a trail of acid can be seen dripping from the creature's mouth. The Spitter's acid might not become acidic until it comes in contact with something in the air. This may be why the acid burns the mouth and nose, but not the stomach. Somehow, the Spitter is able to move and adjust its head, which should be impossible due to its cheeks being eroded away, although it could twist its neck to move the head around. The Spitter's fingernails are very long but do not look particularly sharp, perhaps indicating that the Spitter was very vain before the infection hit. The Spitter's claw attack does about 4 damage per hit.

Survivors

 * If players kill a Spitter with a close combat weapon, they should immediately leave the area before the acid damages them.
 * When the Spitter spits, she'll be slow for a few seconds, then return to normal. Try to use this time to kill her.
 * The Spitter's acid projectile takes a moment to travel to it's target, giving alert Survivors some time to get out of the way. You can also listen for the hacking noise the Spitter makes.
 * Do NOT try to get through a Spitter's acid pool, it chips off health very very fast.

Infected

 * When playing as a Spitter and you're assured to die, try to die in front of the Survivor's path. The acid pool created by your death will delay them and give your teammates time to respawn and group.
 * If you have the opportunity to escape, take it! She who spits and runs away, lives to spit another day.
 * If one of the survivors is incapacitated and there is another survivor near by to revive him/her, try saving your spit until the other survivor is reviving the fallen. This will cause their rescuer extra damage and force them to stop reviving the fallen survivor. Unless it seems likely that you can kill the incapacitated survivor, focus on doing damage to the ones that are up, you might just incapacitate them too!
 * If a Survivor is surrounded by Infected, or even covered in Boomer bile make their day worse by spitting on them. If they are covered in bile they may be so worried about killing all the Infected around them that they will panic and possibly be either too distracted by the spit to kill the Infected, or too distracted by the horde to get out of the spit.
 * The Spitter is one of the most helpful infected. Spitting in survivors who are being choked by a smoker can do extra damage. Also, you can use your acid to separate survivors. For example, if someone is being pounced by a Hunter in a closed area, spit in the survivors path to avoid them saving the helpless one.
 * Your spit causes a lot of panic, because the first thing survivors will try do is get out of it. So having a Charger or a Jockey to catch the survivors while they're trying to save themselves from the acid is a good way to cause damage.
 * Spitters are very valuable in Scavenge Mode, as a Spitter's acid will destroy dropped canisters of gas. Try to have your teammates make the Survivors drop their cans, then let the gunk fly.
 * Use the ability to bounce spit to your advantage to reach into corners you normally cant reach without being exposed.
 * Aim carefully when spitting from a high vantage point. If the goop glob hits any horizontally flat surface that is above the survivors, the puddle will float above them and do no damage.
 * In addition to escaping when possible, try attacking from unusual positions. For example, above the survivors. By spitting down, you can get several attacks in without being killed. If you don't reveal your position, it's possible to incap everyone. This works best if the Survivors are in a cramped area.
 * When playing scavenge mode make an attempt to team up with any special infected that causes them to drop their gas cans and spit on them. If you are successful you will keep the survivors at bay for sometime while the fire keeps them from placing in the gas.

Trivia

 * According to recent gameplay footage, as well as the second Left 4 Dead 2 trailer, the newest Spitter model is permanent. She was made larger, sports a thin, green bra and pink thong under her pants, and leaves a green slime trail from her mouth as she walks. Her legs no longer seem lengthened, but her neck is still extended. Her face is mostly deteriorated away, save for her teeth and most interior mouth tissue. When killed, she will rupture, causing the acidic goo to spill and pool where she was killed, along with her body.
 * The Spitter is currently the first female Special Infected to be playable, followed by the female Boomer
 * The Spitter's goo does not seem to harm other Infected, as they are most likely immune to its acidity. This could be very useful for Smokers, Hunters, or even Boomers, as there is nothing much more problematic for a Survivor than to be blinded, standing in acid, being attacked by a horde, and pounced by a Hunter or strangled by a Smoker at the same time. However, she does not seem to have complete immunity, as there are large, irritated burns where her acid seems to have dripped on. Her mouth and face are also extremely twisted and appear to have melted, most likely due to spitting so much acid.
 * The Spitter appears to have an extreme version of the disease known as acid reflux. This is another reference to Special Infected possibly gaining their powers through bodily properties they had before they turned.
 * It should be noted that in Mercy Hospital, one of X-rays shows an elongated neck. It is possible that this X-ray is a person that has been infected with the same strain of the virus as the Spitter.
 * From the Left 4 Dead 2 Demo, Spitter goo apparently has a slight delay from when it hits the ground and when survivors start taking damage from standing in it.
 * In the achievement icon for Great Expectorations, the Spitter seems to look more like a hunched Witch than her current, in game model.
 * The achievement Acid Reflex is also an achievement of the game Half-Life 2: Episode 2.
 * When playing as a Spitter, you will slow down for about 2 seconds after shooting goo.
 * The Spitter's attack music cue is called Enzymicide, possibly derived from Enzyme and homicide. This perhaps suggests that not only the gastric acid expelled from the Spitter hurts the Survivors but also the digestive enzymes such as proteases which are corrosive to the protein of human skin.
 * On the Spitter's left hand, one can see 4 wedding rings. This could imply the Spitter was in several relationships previous to the spread of the Infection.