Each time I find any issue (including unwatered flowers) I'll get my peeps to clean it up or fix it right away! The only time you'll see wrappers or other issues in my screenshot is if I was rushing to get a screenshot or it's from one of my test families that I keep paused.

I think it would build up eventually, especially with the trash event I haven't thought about whether it would stop once there's a certain amount of trash on the ground or not.. great question!