Should I trust a garage that advertises everything or one that specializes?

I've noticed two types of workshops around here, the ones that claim to do absolutely everything from engine rebuilds to window tinting, and the ones that focus on specific makes or types of work. My instinct says a specialist is better, but I've also been told that generalists can be perfectly competent and often cheaper. I came across zenfoautoservices.ae while trying to gauge which category they fall into, but it got me thinking about the bigger question. Does a garage that does everything actually do anything well, or is it just a matter of them outsourcing the bits they can't handle? I'd rather take my car somewhere that's honest about what they can and can't do than somewhere that says yes to everything and figures it out later. Curious what others think.