Going out for dinner is a big deal for our family, we do it a lot and we enjoy it. However I unfortunately now have a hard time ordering and eating at most restaurants. I have been Paleo about a year and while I might have the occasional minor cheat such as a piece of Halloween candy or even a cookie (I'm sensitive to gluten but can have small amounts of it), and I eat dairy, otherwise I'm pretty strict.
There is something in restaurant foods that completely destroys my digestion though, I assume it is either some kind of oil that they cook everything in or that goes into every sauce, or some kind of flavor enhancer like MSG. I have found I'm very sensitive to certain oils (vegetable, canola) so suspect it is that, but have never nailed it down.
I suspect that the olive oil in a lot of restaurants isn't really olive oil, or is maybe 20% olive oil and 80% vegetable oil, so most of the dressings and even oil and vinegar made at the table are problematic.
I always try to order some kind of grilled protein and cooked vegetables, but even them my stomach is often rumbling on the trip home.
I don't like to make a big deal of it and ask a lot of questions of the servers, and they often don't know how things are cooked anyway, but I have occasionally. There is a diner in our neighborhood where we have breakfast almost every Sunday and I finally asked them what they cook their eggs in, and she said it was a mixture of butter and oil. Which I assume means some kind of commercial griddle grease. This is too bad because it affects my stomach and pretty much every Paleo breakfast item on their menu is cooked in it.
One option that I've found to be reliably ok is Outback, their grilled steaks don't cause any problems and their sides often come to the table undressed so I can control what goes on them, and there doesn't seem to be any bad mojo in the kitchen. Another is kebab places, not sure if it is the halaal meat or something in the prep but no problems there.