Thumbtack appears to be a tool for people to request quotes out of curiosity, with no real intention of hiring a contractor - (maybe it's kids just messing around.?).
I've been w/Thumbtack for almost 1yr and initially pursued leads and spent hundreds of dollars in the first couple of months, only to realize that 99% of these quotes -you would never get a reply back or anything! You are tied to Thumbtack's portal to try and follow up on your leads, which sucks, because you're paying for something that you get no direct way of contacting that lead and most the time the listed lead never has a phone #. There are plenty of other lead generation sites that will do this!
Thumbtack customers are not looking for true professionals, but at best - if it's a real lead, the cheapest price.
As a Thumbtack Pro - save your time & money and put your marketing dollars elsewhere.