From the place that makes the vindaloo that I like the best, if the best chef does it, it always includes extremely small, sliced green chillies which, on their own, are fairly hot--milder than habaneros, for example. Again, not sure if he was winding me up, but after a few go-rounds about getting my vindaloo hot enough, he said that to make my vindaloo, he'd order the chillies from Bangladore instead of the ones they normally used. Dunno if he did or not, but not long after that, the vindaloo got a lot hotter and a lot better.
The guys I was talking to at the place in London mentioned one of their two chefs didn't like to cook phals due to the fumes from the chilli powder, so he didn't cook them properly and just chucked a bunch extra in so it was ungodly hot, but not very good. They said I was lucky the night I was there because I got the better chef that actually prepared it correctly.
Don't know how this compares to other places, though.