To cancel? No way. You won it, its yours. Assume it's a gun illegal in your state (e.g. a semi-auto assault rifle with certain features, that's illegal in quite a few places that I know. Or a dealer sample machine gun but you're not a SOT) -- is that a good reason to cancel? No. You still pay for it, but they can store the gun for you, help you selling it in next auction
But, no cancel of payment.
Regarding inspection, supposedly, you should do inspection in preview. But I did hear some people successfully returned items back to auction houses. I really admire them.
So, don't bid your items yourself. Don't bid high unless you're sure about the condition. Know the local law before bidding, etc, etc. If won wrong items,,, that happens, it's just tuition, not end of the world.
Of course, if you can open an auction business, do it. It's a hot business these days.