Thumbtack is not the only one that is doing this. Avvo has been adding keyword links in their Avvo badges for some time now, and this has worked well for Avvo's Google rankings.
Avvo states that adding an Avvo badge to your profile on your web site is part of completing your profile on Avvo. By doing this lawyers are really just adding links to Avvo, not filling out their profiles.
The interesting Google SEO issue is that when you go to get the html code to add the Avvo badge, it includes a keyword follow link that links to an Avvo lawyer listing page for that same keyword. Avvo does not explicitly tell you that you are adding this keyword link to an Avvo listing page when you are getting the code to add a profile badge to your web site (although if you can read html you would see the keyword text and link). But non-technical lawyers, as most lawyers are, who go to the Avvo badge/widget page will think they are just adding a link to their profile.
The Avvo badge is actually rendered in javascript. You can just remove the html keyword spam tag and the text completely from the raw html, and everything in the badge from a user perspective, the graphic, text and the link, still shows up through the javascript. This indicates that the only real purpose of the text link in the raw html is for Google SEO.
This was discussed on the Lawyerist site in a post titled "How the Avvo Badge Promotes Your Competition" (although the real title of the post should have been "How the Avvo Badge Promotes Avvo").
Avvo has been getting topic specific lawyer websites using topic specific lawyer keyword text links to link to topic specific Avvo lawyer listing pages.
Avvo states that adding an Avvo badge to your profile on your web site is part of completing your profile on Avvo. By doing this lawyers are really just adding links to Avvo, not filling out their profiles.
The interesting Google SEO issue is that when you go to get the html code to add the Avvo badge, it includes a keyword follow link that links to an Avvo lawyer listing page for that same keyword. Avvo does not explicitly tell you that you are adding this keyword link to an Avvo listing page when you are getting the code to add a profile badge to your web site (although if you can read html you would see the keyword text and link). But non-technical lawyers, as most lawyers are, who go to the Avvo badge/widget page will think they are just adding a link to their profile.
The Avvo badge is actually rendered in javascript. You can just remove the html keyword spam tag and the text completely from the raw html, and everything in the badge from a user perspective, the graphic, text and the link, still shows up through the javascript. This indicates that the only real purpose of the text link in the raw html is for Google SEO.
This was discussed on the Lawyerist site in a post titled "How the Avvo Badge Promotes Your Competition" (although the real title of the post should have been "How the Avvo Badge Promotes Avvo").
Avvo has been getting topic specific lawyer websites using topic specific lawyer keyword text links to link to topic specific Avvo lawyer listing pages.