Answer:
There are several different kinds, but the one you pick doesn't do its job. What is it?
Looks like water, but it's heat. Sits on sand, lays on concrete. A play on the eyes, but it's all lies.
I usually wear a yellow coat. I usually have a dark head. I make marks wherever I go.
I know a word of letters three. Add two, and fewer there will be!
It is worldwide, but once only a spider could weave one
This food is a tortilla filled with cheese and sometimes chicken before being heated or cooked.