I would really have to think this play is -EV in the long run. With bottom two pair here and this much action I would have to think you are either way behind or barely ahead, and against most players you won't be ahead. I would expect to see hands like T9, T7, J8, and 68 more often than I would a big drawing hand. And yes, even though you were correct that they were both drawing they still have a lot of outs against you. And there will be times when you are drawing almost dead here so that's something to keep in mind.

Nice pot anyways, though.