I would never have enrolled at 'dating' sites, but not for the same reason you judge them... For me, it's not because I feared them lying to me, but more because I don't have the kind of personality that could write an ad for myself or respond to one. It seems to me to be a very loaded place to say "hi" to someone. The way I did it, I began flirting with someone here I already knew as a friend, our relationship did not begin as dating screening, it began as good conversation.
But, for more outgoing personalities, it ~can~ work. I know someone who met and married through an online singles service.
I just recently signed up to an internet dating service. So far it's going pretty good. It's not as scary as I thought it would be.