I describe and photograph all my stamps as well as I can, but all my stamps are sold "as seen", "uncertified" and "ungraded".
What you see is what you get.
If a buyer manages to spot a fault under their electron microscope or other sophisticated equipment which I do not have, that is the buyer's problem, not mine.
If you have any doubts, do not bid.
If you seek absolute perfection, then only buy stamps that are certified and graded, and be prepared to pay the full market price as well.
If you want to have the thrill of 0.99c auctions and maybe get a bargain, then bid. This is what eBay was supposed to be about.