You cannot go wrong with the primary colours, it get a little harder when you need a Pantone© Colour match chart to determine where they are into, let alone adjusting for the light level or if they washed it with something else!
There are other lists such as the one at the In Search of Men web site "Codes". There are lots of things which signal what the guy is into - like if you are in full leather you want a leather guy, if you have a paddle hanging from your side it is planned to be used, and so on. This is fine for the clubs and a gay space - but Hetros copy gays boys without understanding any unspoken implications, its just fashion. They are just copying a guy in the street just like any fashion.
This has now transformed into BDSM guys being less subtle about their dress code - especially in London where you are competing against exotic 'high fashion'. In other countries (previously gay strong holds) there is almost no signalling - like in Germany they have an expression "you have to open the box to find out what is inside" - this has the advantage that none of your signals can put off the other guy; you take me as you fine me!
Much of this is simplified when a guy into Fisting has red boot laces, red braces, red strips on his jeans, same with yell for pissers, however White replaces black. That is just as your boots came with back laces your leather jeans came in black this is take to mean Vanilla, where as white laces in your boots means heavy SM.
If you are in Germany and a skinhead it can also mean you are into White Power and there are political sensitivity about such things. In the past, the UK Skinhead with Red laces meant British National Party, Skinhead with White laces meant National Front and yellow meant another - there were no Gay Skinheads and you are stating just how hard you were. So if you are not gay White Laces are for White Power and Red Laces for socialist (USA:bit more left than democrat/liberal). If you are gay skinhead then you are stating a sexual preference. It is not just upto the observer to work out if yiou are a gay skinhead or a hetro skinhead or just a fashion skin! See Boot Laces