Yes, perhaps it wouldn't be bad to have bots give up trying to get to a particular WP after the x-th attempt. While the problem is entirely wp-related (i.e. it's the waypointer who f*cked up and not the bot coder), it can't hurt to have a bot that can compensate such errors to a certain degree. Besides, I don't think it's too realistic if a bot never gives up and keeps trying the whole round - especially if he's on a mission.
Here are two examples :
1) I once had a bad WP for de_heat (not made by me, of course!
) which had a WP suspended in the air somewhere near a hole in the floor where bots could get down one level and drop on top of a stack of crates. Then they tried to reach the mentioned WP, but it just floated in the air and they fell down from the crates way before reaching it. So they walked back to where they came from and tried again. And again. And again. And eventually, every bot that passed this place once would be trapped in a loop, trying forever to reach that darned WP.
2) In the WP for cs_1337_assault a friend of mine sent me, there was a wrong connection up a crate. A T bot (the last survivor of his team) tried and tried to get up there - meanwhile, the last CT had activated the hostages and was coming down to the main room of the warehouse. There he heard the T and froze, then took some steps back and forth... the T bot kept trying to reach that stupid WP, and the CT "locked" onto the T - the round ended without any further action...