Yolanda put it better than I would have. i judge dating sites almost entirely on the trust question now. You cannot really talk about dating sites without talking about local activity levels.
The geography of it's what separates a good week from a wasted one with dating sites.
In practice, dating sites live or dies on how quickly you get going. Nobody warns you that dating sites depend so heavily on not oversharing.
The honest tradeoff with dating sites are the learning curve against convenience. What am I missing on dating sites?
Your mileage on dating sites for bbw that are body positive will vary, but that is the pattern I saw.