Their refund policy literally states:
"Neither Envato nor authors are obliged to give policy refunds in any of the situations listed below.
* The item did not meet your expectations or you feel the item is of low quality"
See it here: https://codecanyon.net/page/customer_refund_policy
What this means is you can buy a plugin that is utter trash and does not work properly or meet expectations and not be entitled to a refund. I had perfectly good grounds after I bought a plugin which didn't do exactly what I expected it to do and they denied my refund.
It should also be noted that when you make a paypal dispute, they go ahead and lock your codecanyon/envato account!
DO NOT BUY FROM ENVATO / CODECANYON.
P. S they remove your reviews if they are not positive as many other have said.