Are you saying that you accept no fault for not inspecting the motor better?
Are you saying that you believed that you could ask for a refund if you did not meet your expectations after your "post-purchase" teardown?
Did you ask the seller if he would let you return it if you didn't like it?
Did you think it had a warranty? if so, you would have voided it by tearing the motor apart yourself.
Did you think the seller had recently performed a full inspection on the internals of that motor?
YOU bought that motor based on the preliminary inspection YOU performed and the buyers word. Now you want your money back?
Its not like you paid $1k or more the motor dude. You got a great deal, needing bearings or not. You bought a USED shortblock without looking at it very well before putting down a whopping $200 + a used catback. Stuff like that is always AS IS, its just a no brainer.
Do you try and return stuff at garage sales too?