@Khun *****
if an embassy issued the visa based on a dodgy work contract it's their fault. At many embassies they won't ever issue the visa until they're 1000% sure everything is legit, and I think IO at airports know that. Thanks to my DTV being issued at Seoul, Korea, I've never been asked a thing, while some issued at neighboring countries have a bad reputation among IOs at the airport, for the same reasons you mentioned.
PS: Seoul, Korea is not the only one known for strict vetting