Yes, nearly all of them have had Dean quite sober. In fact if you'll recall he got majorly pissed at Sam for getting drunk on the job in Playthings. We've NEVER seen Dean drunk on the job. Or even particularly tipsy. Once with Gordon he had quite a few AFTER the job was over but not enough to make even act tipsy. The one time he had a hangover was last season in Provenance after a night out with two girls. :) The last episode doesn't count because Sam was clearly exagerrating because he dislikes Dean getting information in bars, he always gets on his case about, even when Dean gets good information.

Otherwise we see him have a beer, almost always at the same time Sam is having a beer. Or he'll have a drink at a bar while trying to get information, which one or two drinks does not an alcoholic make. Dean's 6ft 1 and has plenty of muscle, it would take rather a bit to get him drunk.