I've used both Lava and the Springstreets network (found on nerve, salon & onion). What I found was that because of the targeted demographic of Springstreet's host sites, it was much much easier to find people who share common interests. On lava, one has to wade through hundreds of profiles (many of which do seem to be fake) to find people with similar interests. Not sure there's a way around that. Maybe they could have designed their profile questionaire to be less generic?

One problem I've found on Lava is that there is no reverse match for age. That is, I can say I'm looking for somone between 30 and 40 years old, but I can't say I'm looking for people who are themselves looking for people between 30 & 40. Problematic because some peolple are looking within a very narrow age range.