Considering the extent to which cigarette vendors around here keep their merchandise locked up, I don't think they're willing to take on a lot of "I hope these bitcoins are legit" risk.
Merchant software can listen to the network for 10 seconds. If no contradicting transactions have been broadcasted, the probability of the bitcoins not being legit is EXTREMELY small. You only need confirmations for large transactions. Zero-conf are completely safe for the large majority of transctions.
Bitcoin-type technology has tons of potential, my friend.
Bitcoin-type technology has tons of potential, my friend.