I've never used a reader. I have friends who read my scripts (and I read theirs in return). I'd advise against paying readers generally, but if a writer feels the need to get feedback, she should get it from a pro with film/TV credits.
Also, if you're able to get it into a prodco, it'll be judged against whatever else is circulating within that genre, so that's another reason for at some point to get professional perspective, whether friends in the biz or if you have to pay for it.
