This is analagous to the enforcement of the time limits b/w points. I don't watch a lot of live doubles, but I've been to college matches and seen some pros at Indian Wells and Miami. I have never seen the refs call hindrance for doubles teams that communicate during the point. I don't argue that they couldn't and perhaps you've seen a match where this occurred.
As amateurs it is worth the risk of losing that point to give my partner an extra second to bail. I figure if they're the sort that would claim a hindrance for that, then they'd be the sort that would try to do some damage w/ their overhead.
I think there are unwritten rules of sportsmanship on the court. I've been lucky having played in Texas and NY w/ people who were good sports (not counting my brief stint in mixed dubs).