Depends how many total founders there are, and whether the one we were dubious about was CEO. I don't think we'd fund a co if we didn't like the CEO. Whereas if there were 3 founders and we disliked one who wasn't the CEO, it probably wouldn't be a problem.

Incidentally, you are probably overestimating the degree to which you'd lower their chances. We often fund groups on the nth try. PagerDuty was those guys' fourth try. Even Dropbox was Drew's second try.