Before i learned scheme(I don't know CL), i didn't know how to write python. I knew how to write python syntax, but had no idea how to write code that doesn't suck. I still write bad code, but at least i know when its bad and i need to change it. Scheme thought me how to spot ugly code. I still use for and while loops(recursion is expensive in python, and you shouldn't write scheme in python) but i learned to write small and simple functions and combine them in smart ways(list comprehensions, maps, filters, decorators...). I guess i knew that from reading about the unix philosophy, but it took me to see it in code to understand it. So learning scheme might help you to be a better programmer, or it might screw you up and you end up writing stuff like this http://www.pick.ucam.org/~ptc24/yvfc.html

p.s. I've never written anything longer than a textbook exercise in scheme, so i don't know if you can actually write real stuff in this(or how hard it is) but playing with it is really fun, you should to it just for that.