The only straight in this bar

A fair amount of publicity has attached to this move by a Melbourne bar to refuse entry to heterosexuals. A few fairly obvious objections (even disregarding the discrimination thing) sprang to mind. How are they going to tell? My haircut and chinos might admittedly mark me down as hopelessly straight from the very first sight but I have my doubts as to whether anybody's gaydar is 100% effective. Tim suggests a more rigorous entry system (so to speak) but I doubt whether even Melbourne would go quite that far.

My next thought was probably that this was akin to those '21 and over' bars. The point is not to ban 20 year olds, but rather to have an excuse to evict 16 year olds with fake IDs. Similarly here, I suspect the rationale is to have an excuse to exclude people who want to cause trouble. How do you recognise them though? Most of the cliches of men who go around bashing up gays are, um, slightly ambiguous. Skinheads in jeans and white T-shirts? Blokes with tattoos? Large groups of men? Seeing the problem yet?