That's fine? I mean, this is how the world works in general. Your friend X recommends Y. If Y turns out to suck, you stop listening to recommendations from X. If Y happens to be spam or malware, maybe you unfriend X or revoke all of his/her endorsements.
It's not a perfect solution, but it is a solution that evolves towards a high-trust network because there is a traceable mechanism that excludes abusers.
