I face paint at children's parties, and the saddest/most annoying aspect I encounter is the vulgar trendy club music that's played. 5,6,7 year old girls dressed like twenty-something club hoppers and singing along because they know the words to all the songs.
I take my 3 year old son out to the park or the library each weekend. Often in the couple of parks we go to there are large familly parties and similar to your example people play (what I think is) some pretty innapropriate music for their kid's party. Makes me wonder...