Never understood the Lisp-mania: how could you like a language where you won't get a type error until after you run the program?
It bites me in Ruby/Python, but not in Lisp.
Most of the time, you're just map, car, cdr, mapcar, reduce, fold, etc in Lisp. Functional iteration/processing semantics are the default in Lisp. Common Lisp makes it VERY obvious when you're not using a standard data structure so it's hard to mess up.
Ruby and Python proliferate arbitrary Object-Oriented interfaces, combined with dynamic typing, it's easy to get the wrong instance of something-or-other and fuck it up.
Contrary to popular belief, Common Lisp code tends to be more consistent in terms of how you interact with your data, even if they go on flights of fancy re: Reader Macros.
I say this as someone who works with Python daily as my working language and grew up with a copy of this:
http://www.cs.cmu.edu/afs/cs/Web/Groups/AI/lang/lisp/impl/cl...
I'm fully aware of the errors that can arise from dynamic typing in Common Lisp. It's just not my experience that it's that big of a deal.
The reverse association list is contrived compared to the issues one can have in Python or Ruby. Most people just use association lists the normal way and use rassoc as needed.
Lets not kid ourselves and pretend that a reversed assoc list is used in place of a normal rassoc or find :key #'cdr.