This 'Hidden Feedback' seems to be a growing fashion on AW. Lots of girls with plenty of +ve feedback are hiding it too.
I can only guess a few reasons..
1) Those leaving the feedback are her mates, not genuine customers.
2) To cover up a public audit trail of who she has been with
3) To cover up any potential bad feedback which may land
4) To discourage blokes from writing a huge great diatribe of how good she is in the hope of a freebie next time.
As for being a scam, maybe, but can't comment without seeing the links.