I was looking for someone to haul a half-truck load of construction waste. From a google search I contacted a few ads, some being with Thumbtack. I got 2 emails back saying a had a bidder, $50. There were no links to reply to, so I looked up one of the people, phoned them, and they said they didn't know about the bid. They asked me to forward it to them. They also said they would do it for $130.
Don't waste your time trying to use Thumbtack - it's frustrating and you'll probably just waste a lot of time.