This is an interesting thread as I am currently in New Zealand where unprotected oral (fellatio and cunnilingus) is against the law with prossies with the threat of a hefty $10,000 fine for both parties. I kid you not. Interestingly, the one punt I have had over here the girl categorically refused owo but happily received RO uncovered without a dental dam. Just goes to show that prossies are the same the world over.
Personally, I really enjoy daty and if the girl is clean and fresh can often make a real pig of myself. As far as a dam is concerned that would put me off as much as receiving covered oral.