I have found that my chicks are likely to get pasty butt if they are too warm or the humidity is very low. I check their bottoms every night when we clean the tote they live in. If they're clean, no problem. If they have a little poo stuck to their vent feathers, I set them aside in a separate box till I've checked them all. Then all those with a sticky bottom, even if it's just a few sticky feathers, I take into the bathroom and use my wet fingers to clean them off in the bathroom sink, just wetting my fingers under the spigot with warm water. Then I dry each bottom off with a dry paper towel. If they're very wet I may use a hair dryer on low to fluff them up a bit before putting them back in the tote with their siblings. If you check them every night they won't ever get big nasty wads of poop on their vents which can be life-threatening.