To be honest, the police won't care about a smalltime purchase on ebay, whether they're stolen or not (no offence intended) . They have far bigger fish to fry.
I like to assume that people are honest, though I am let down occassionally. Give the seller a few days to reply, then start an 'item not as described' dispute with ebay and paypal (if applicable). Give that a few days then esclate to a claim. If the seller fails to repsond throughout all of this, you will get your money back and you can do what you like with the boots. THEN, and only then, can you legitimately leave scathing negative feedback and have no come back whatsoever. Be as harsh as you like.
The trick to ebay is to be patient and calm with you have problems. I've had an abusive seller recently too who accused me of all sorts - theft, deception, deliberately planning to rob her... she was the one in the wrong! I contacted ebay about her and they went though all the history from the transaction and disputes - I was completely above board and protected by ebay.