Sam2, if the garbage can has fleishigs, throwing the pizza out could be bishul basar bechalav which is assur even if you do not eat it.
yitayningwut, one of the meforshim there says specifically that the achbera dedavra is the squirrel. Rashi says so as well.
yungerman1, even tho the drop should be battul, in this case we don’t allow bitul lechatchila and it’s assur for you. In addition, if he says it adds flavor it could be avidi letaama, although this area is a bit grey- in metzius it shouldn’t add a noticeable taste. This is similar to the machlokes about sherry casks in liquor.
Here’s a common one. You buy 100% canola oil in the store without a reliable hechsher. not a drop of lard is in there in metzius, and yet halachically it’s treif. Why?
Why would carmine coloring be or not be a problem?
Most kosher candies are covered in the secretion of the lac bug, aka shellac aka confectioners’ glaze. Why would this be allowed?