Chances are he would find a date who has similar interests - and there are lots of free things to do, walks, parks, bike rides, picnics (grab something from the dumpster at Subway before you leave)
People are very wasteful. Just because something goes into the trash doesn't mean its without utility. It just means someone decided it didn't have any utility for them. Many perfectly fine things go into the trash everyday. Letting them rot in a landfill instead of being recycled seems way more distasteful than a smell that will wash right off.
If you are going to try it, the first rule of dumpster diving is to leave the site in better shape than when you found it. If you make a mess, you clean it up. Its the decent thing to do, and helps keeps the neighbors calm. Its an oddly invasive act, as peoples trash is basically a story of their life, so anything that soothes people about you going into a dumpster is good.
Personally, I did it largely for the sense of adventure. Its like a modern day treasure hunt. The fact that I was able to furnish my apartment very richly for nothing was a bonus.