Tbh I've been in a lot of pubs with reputations as being 'hard' or 'rough' but generally I've never had any bother. Go in, keep myself to myself, have a drink and leave. Always find nobody bothers me or the group I'm with.

Funniest thing I've seen in a 'dodgy' pub was identical twin brothers battering each other in The Good Companions in Oxgangs.