Bars seem to pick and choose which forums they post updates on - sometimes due to familiarity and friendships, sometimes due to the activity of the board.
Very few post on all the lbs forums. It does take time to post updates, and especially photos, which can be problematic if the uploader doesn't work well, or the internet connection is slow. Some bar owners are techo-phobic, and some might not have enough time - but certainly the benefits for those who do post updates is clear. Cocktail and Dreams has been able to maintain enough business to keep going despite surrounding bars (gg and lbs) going under due to lack of business. Lita's Bar is getting business as well, and so is La Bamba.
Interestingly enough some bars that were heavily promoted by Gutsy Bastard on several forums are facing difficulties, Darkside and Paradise Club so advertising is not always the solution for increased business.