Readability in any language basically comes down to whether the programmer formatted his code in a non-malicious way (which is the case 99% of the time) and used variable names you are familiar with. I'd be more worried about the meta constructs in Lisp (and whether they are sound). To be able to reason semantically about a program is something that is made easier by static typing and static name resolution. Instead of constantly worrying that X is not defined where you think it is (because some dynamic binding system has yet another edge case you forgot to think about or discover), you just always know where it's defined.
