Normally I am looking for bagged grass clippings, but with all the rain, the bagged ones stink to high heaven if I don't pick them up on the day they were mowed. So no bagged grass clippings today. I search for the nice clean piles and use my seed fork to load them. The piles are normally just wet on the top, and they do smell but not as bad as sour grass stored in a bag a few days. The last pile I picked up had just been cut and it had that fresh grass smell.
People here in town (I have my regular times and routes, have to stay ahead of the city crew) mow their lawns then many just pile the grass clippings out by the road, a few go to the trouble to actually bag them, after running the routes for a while you learn where to go, and what to avoid (people with pets love to put dog and cat poo in their bags).
I can never tell what type of poison people have used on their lawns, but so far none of the grass has caused me a problem. However I did just buy two bags of weed and feed, and I noticed that there was a banner on it stating it was the newest science available, and warned against using the first two mowings in compost. So that may get to be a problem, and I may have to extend the time before I use a batch. I know at one time there were some products out there that would not even break down after a year, but I don't think those are too commonly found unless the lawn is treated by a commercial lawn company.