I know that in my Thai and Indian cookbooks occasionally they use a teaspoon of sugar here and there, but it didn't seem like much. When I use the recipes at home I omit the sugar. When I'm out at a restaurant, as long as the food doesn't TASTE sweet, it's pretty much OK with me. This is just me though...you'd have to see how you deal with it yourself.

I'm not enough of an expert yet to know what dishes don't have sugar added. You'd probably know better than me!