Hi Lyndsay. I read your letter ("The darker the skin, the smaller the wage" Ajarn Postbox, 5th February 2013) and can completely understand the shoes you're in. I am an American (but of Hispanic descent). When I first moved here, I too faced some of the same likely scenarios you seem to have faced. Bottom line, the Thais always seem to place 'image' above everything and anything else important and frequently favor those with light skin, blonde hair, and blue eyes. * (That's why 95% of ads always insist on attaching a photo to your resume).
The way I finally started to see it, one may have all the qualifications they believe to get the job, but there's one 'qualification' truly desired that they don't always mention. As a result, I highly suspect I was dropped from a potential list of candidates from a handful of jobs just because of an appearance conflict. Yeah it's prejudice at it's best though and you're also right: it's definitely sending the wrong message to everyone - foreigners and Thais alike. I think that with a thinking like this, it could possibly inhibit others to think the same way and/or that this sort of profiling/generalizing is "an okay practice".
You're right though. A person's image should NOT play a part in whether or not they can do the job. Unfortunately, as a frequent saying goes, "This is Thailand" and I strongly agree that things here can be far from perfect, but with some patience and determination, I think everyone can eventually land a good job and where acceptance can be made by all. You must be patient though. It took me a bit of time before reaching the step I've reached on the corporate ladder. However, finally rising to the place I felt I should be in, I'm very pleased and satisfied where I am now. That and I honestly carry my head a little higher because of all I've been through. Best of luck to you Lyndsay!