The Quandary Of Watermarks

So if I understand this correctly...

It is sometimes possible for the watermark on a stamp to be virtually undetectable. And for some countries, there can be two separate issues of a particular stamp, in separate years, which are identical in every way except that one was issued with a watermark while the other one wasn't. Which means that, technically, you can have both stamps in front of you but have no way of knowing that they are not actually the same stamp, because the original watermark is now invisible.

Furthermore, and even more unsettling, any unwatermarked stamp that has a watermarked identical counterpart can not technically be verified, since the possibility is always there that it originally was watermarked, and you just can't see it anymore.

What's an obessive compulsive to do? :)