I haven't been to Thailand since the late 1980's but my favourite then was Hogs Breath, upstairs on the left.There was also one on the ground floor right but I cannot remember the name other than that of 2 of the girls (!). I used to go down to Soi Cowboy as well. Tilac bar.
This was in the days when Golden Palace hotel in soi 1 and the stalls and bars in the area opposite soi 1 under the flyover and along by the rail track were still there.