Another option might be, require people to post under their real name. Boy, oh, boy – if this happened, the less scrupulous ESL forums would fold over night – and our industry would be a better place.

But scrupulous ESL forums filter out adverse posts about ESL employers who pay advertising fees to said forums. I, for one, am disinterested in reading censored ESL forums; I won't allow myself to be conned by one-sided media.
The only way our industry will be a better place is if ESL employers, by and large, were to take the lead by behaving honestly and paying worthwhile salaries. If they do so, they'll be able to fill many more of their vacancies with professional teachers rather than with irresponsible malingerers! Then the number of unfair complaints on less scrupulous ESL forums will be much reduced.