I get that residual smell from time to time with my buckets. My fix has been a 24 hour Oxiclean soak. If that doesn't work, I'll give it another 24 hours with PBW. I haven't had any trace of a smell after that.
Is it a good idea to use the buckets for both beer and wine? One of the LHBS i visit tells me to use separate, as they said the yeasts used in beer will kill the yeasts used for wine and vise versa....and my not work out if using the same buckets. I found it weird thinking that it wouldn't matter with a good cleaning, but hey, what do i know right? lol. I just nodded, agreed and walked away.....So any truth to what they told me? or were they just trying to get me to get another bucket? (which i didn't)...
Thanks for the input guys. I did the oxiclean soak for about 8 hours. It still has a beer or alcoholy smell. I'll try another soak and let it dry outside awhile.
As far as beer yeast killing wine yeast, after soaking in oxiclean and sanitizing I don't think there would be any yeast still alive.