I did a few reopen reviews. For some questions it was not at all apparent why others wanted to reopen the question. Perhaps it would be nice if the first user casting a reopen vote was asked to (optionally?) add a reason, either similar to a bounty notice or as a regular comment?
Evaluating a question for being re-opened and evaluating a question for being closed are identical. It's just a matter of whether the question meets the criteria for being a valid question on the site you're reviewing for. Each question really should be reviewed independently of any hints, close reasons, etc. We're not racking up votes for the sake of votes, and we certainly don't want to give into the hive mind mentality. If we voted to close something just because someone else did, it wouldn't require five votes, now would it?
If you read the entire question and the comments on it, it should be pretty obvious whether or not it's a good candidate for the site and should be reopened, or if it should remain closed. If you've done that entire read through (not just skimming, mind you) and you still can't decide, either read it again or skip it. Discretion is the better part of valor.