For the Homeowner perspective:
Home Advisor leads potential customers to believe that they can give them accurate costs for different projects and also provide them with several options of willing contractors to service them. But they are primarily interested in having people request a "Lead" so that they can then relay it to more than one Contractor and charge each of them a fee. Contractors get charged whether they accept a "Lead" or not. So if the description given by the homeowner is less than described, it is frustrating for the Contractor. Another problem is that when a Contractor meets with a potential client, those clients often have an unrealistic idea of the cost of their project ( usually precipitated by Home Advisor's unhelpful cost estimates).
For the Builder/Contractor perspective:
Home Advisor makes money from Contractors by charging them for each and every "Lead" that they provide to them. "Lead" costs range between $50 and $250 each.
From personal experience; I received around 20 "Leads" over a 6 month period.
18 of those "Leads" were ones that I considered bogus. The "Leads" were either not for what their descriptions said they were for, people just trying to satisfy a curiosity or they were asking for services at Ridiculously Low Prices (three of the "Leads" were asking for someone to build them a 1600 square foot custom home including land for between $100,000 and $200,000). I tried to not get charged for these "Leads" but was told that they considered them to be legitimate "Leads" and their would be no credit. Although I did receive credit for 5 of those "Leads", it still ended up costing me over $1,000 before I decided to quit their service.
It is true that Home Advisor does come through with some good leads but the way they aggressively pursue money for 'Leads" gives a foul taste to their business model.