Seeking Clarification Non-imm B + Work Permit

Hi

I read that anyone living in Thailand "working or conducting a business" is meant to have a non-imm B & work permit - even if unpaid work. The page linked below also makes mention of the term "investor"

http://www.mfa.go.th/web/2482.php?id=2492

OK so if you are employed by a Thai business or you run a thai registered business then it is fairly cut and dried. But beyond that there has to be a huge amount of 'grey area' surely? Look at writers for example, people running internet businesses (living in Thailand but trading outside it), people 'flipping' condos, day trading in shares on the SET (+ overseas exchanges), just holding Thai shares or managed funds! and so on and on.

I am interested in two things, firstly to see what the law actually says about where to draw the line. There must be a more precise description than the Ministry of Foreign Affars page above, surely (?)

Secondly what is the score in real life? what do people actually do about this? and what is actually enforced?

Thanks for whatever info you can throw at me on this one.

- CB