Oh yes, they can be very conservative and small minded, with no 'world view' whatsoever. Staff rooms were pretty boring places, I remember, and very cliquey. I never could break into the lunchtime knitting circle
I was still in my 20s as well, with a wife and kid. It's true that some people do have a negative perception of Thailand, and I've come across it myself, and I can see how a single male in his 40s who's lived several years in Bangkok might be viewed by some people. People do judge. Thailand TEFL experience will do you no harm whatsoever, but other factors closely connected might not work so well for some, depending on the individual.