I don't know what you mean about Thailand being a "diverse factory." Do you mean it has a mix of different ethnicities (diverse), or do you mean it is churning out unqualified graduates, like a factory for cheap goods (divers factory)?
When I dived in Thailand, it sure did seem as if they had a lot of IDCs. Does that mean they are bad?
People on ScubaBoard tend to mock programs that take relative beginners and turn them into professionals in what they feel is too little time. I knew a Course Director who said he had had that feeling himself until he had someone coming in from such a program looking for work. He said the guy turned out to be excellent. I know someone who went to such an instructional program as a DM and came back as an instructor, and he was a totally new and very highly skilled diver. It turns out that a diver doing several meaningful, targeted dives per day for a month or two can learn more than someone doing a bunch of beginning level, follow the DM dives spread over a couple of years.
So that doesn't tell you where to do your training--it just means that you shouldn't necessarily dismiss an entire region based on something some random person believes.
The one suggestion I do have is that if you really want to do this as a profession, go all the way to instructor. Most of the DMs you see in the better dive operators are actually instructors. The operators want people who can handle multiple tasks.
