There are a lot of good responses here. I agree with the CIJO. I also carry extra logs, baggies, trash bags and SWAG. I go to Walmart and buy 97 cent hot wheels. I drop them off still in the package. If I find a well hidden large cache I'll drop one even if I don't find anything I'm interested in. I generally like pins and buttons and signature items.
I also find that caches further out on the trail seem to fair better. I was hiking the Pacific Crest Trail near Big Bear and the caches were rather full and well maintained.
I also like the micro, but how many LPHs do we need? I enjoy driving 30 miles out of town to find a micro way more than pulling up to a lamp post at the local middle school.
But back to SWAG degradation. Those of of who trade need to keep our standards. There will always be those who don't. My favorite quote, doesn't quite fit here but is close enough. For evil to win, good men need to do one thing, nothing. To paraphrase, For trash cache to win, good cachers need to do one thing, nothing.
Fight the good fight. There are others behind you who are worth it.