I was playing a match this weekend and we were all square after three, when my opponent pulls hooks a ball into the woods on 4. I hit a good tee shot in the fairway. I've got a pretty good line on where his ball went in, and it's a huge mass of tall weeds, some pricker bushes, probably poison ivy, etc. I'm walking and he's riding, so he's already in there looking, but not in the tall stuff where his ball has likely gone in. I make an effort of looking, but not in the tall shit. He ends up declaring it lost and hits another, ultimately picking up and conceding the hole.
This is a guy I'm friendly with and he's a past president, but there's no way I'm going into the tall shit to look for his ball. I've played matches against people who won't help at all, and I find that behavior to be bad form.