I don't venture into categories looking for threads anymore unless I'm extremely bored. For the most part I read whatever is headlined on the front page. I do this on a lot of sites now and have for a few years.
Occasionally something from the subscription-only forums makes it on to the front page that interests me. It doesn't happen often enough to make me want to purchase a subscription though.
It would be nice if I could use my debt card, Paypal, etc to purchase credits that grant me participation to these threads on a per-thread basis.