Common Lisp for Schemers

What's the best way for a Schemer to learn Common Lisp? It seems like Scheme itself is a more beautiful language, but the efforts made by many implementations to make Scheme useful "in the real world" lead to a big ball of mud™. Does Common Lisp avoid this problem? Should I keep trying to learn different Scheme implementations instead until I find something I like?

>>7
Macros are just a source of bugs. It's like fucking copy, paste and replacing pieces of text. Your example is naturally done without dirty referentially opaque tricks: just use a reader monad. It's just that I'm too lazy to do it myself..