Polerion's Attack: Chigorin's Countergambit

In the Variation 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Na5 6.Bb5+ c6 7.dxc6 bxc6 8.Qf3 the sack 8... cxb5 is a rare continuation althought engines suggests (depth 28) that Black have equallity.
My question is, is their someone how knows why 8... cxb5 is a ´bad´ move , which nobody wants to play?

PS: Yeah my english is not so great...

Well some people play it. 8...cxb5 has a less good reputation than the alternatives, but it is playable.