If a problem is brought up with management and not resolved on next visit, or if the customers complaint is dismissed in a rude fashion, I see no reason why the punter shouldn't post about it as long as it is not done in a malicious manner, and don't keep digging up old posts to flog the same point. Before joining forums I used to wonder if some of the poor treatment I got at some venues was all in my imagination or if I was making mountains out of molehills, but then after reading complaints from others realised it was indeed not my imagination. By the same token after reading some alternative points of view I've reconsidered my stance. Constructive criticism shouldn't be discouraged, and sometimes when a business sees this criticism in a public forum it forces changes (such as when an owner sees how some of their rostered staff behave in their absence). Keeping criticism constructive and not overly emotional or malicious really can help everyone. Problem is sometimes it's hard to know what complaints are legitimate and what aren't.

On another note. If you have your phone handy, and the shop posts legit photos and try the switcheroo, simply show them their own photos with a raised eyebrow. Not a foolproof solution but certainly worth a shot. If the charade is continued then move along. I've decided I'm old enough now to not have to put up with behavior I don't like. I'll offer a chance but ultimately nobody likes their emotional intelligence being insulted.