I deal with them regularly(4 dumpsters) I have a decent method down. First, I cut all of the bags open, so they only get out 1 yogurt cup at a time vs. a whole bag. Second, keep applying amonia, use a spray bottle so you can cover the top layer of trash, after a couple of days of tasting that, they usually move to the bar's dumpster down the road, and stay there for the rest of the summer.