I had this exact situation a few months back where a buyer had left a very positive comment but with a big red dot.

I read up on the policy and that suggested to try and negotiate with the buyer first as you only get one shot at having feedback changed/removed.

After having received no response from the buyer I then contacted ebay about it.

They removed it straight away as "accidental negative feedback" while I was on the phone.

So I think it very much depends on the person you talk with as to what happens.