If i cant find a cache, I usually just come back a couple days later, take a different look at it, and it usually turns up, I haven't been to a cache yet that was missing, so for me its a pretty rare occurance
I can't imagine using a hollowed out bolt and hope I never come across one. I may be in the minority, but to my thinking, a hollowed out bolt is just wrong. So now I have to start jiggling all the bolts when I am on location .
Lol they're not all that bad, just found this last week