I dropped a cam (red metolius) from half way up Yak Peak (~1 pitch below where Yak crack and Reality Check meet). Two weeks later I saw a guy carrying it on his rack at Squamish (it has very distinctive markings). He said he found it on the trail at the base of the climb.
If you had been the guy who found it, would you have used it? How about if you had known how far it had been dropped? That same trip i found a red tri-cam on the peak of Yak. I assumed it couldn;t have been dropped far, but the sling looked ratty. I intended to replace it, but then i lost it somewhere.
Generally, for gear bootied from cracks, use your common sense. If it looks OK, it probably is. If it has a sling on it, the sling should be considered suspect and replaced.
This past summer i found two nuts at the base of Bugaboo Spire NE Ridge. One was in like new condition. The other, the cable was rusted to shit. Use your common sense.
Also, i use bootied biners for more mundane things like racking nuts, carrying my nut tool etc. and they will be the first to get left behind if i ever have to bail.