>Don't normal thieve's counterfeit items crumble after a time?

Some things will cause them to crumble.

>Did the one Qaledus made have this same limitation?

Not the same limitations, no.

>It would be pretty crappy if it was such a good fake that there
>wasn't a reasonable way to determine that it was, indeed,
>counterfeit.

Reasonable is you suspected something, maybe. ;)

In the event the larger.. situation.. that led to this is still
unfolding, I'll only say that sometimes trust and need intersect
in such a way that even someone who is surrounded by evil people
that they've treated like garbage will let their guard down. And
when they do, they stop looking for things to be suspicious about.
That's when they get whammied.

Happens to supervillains all the time. ;)

"When everybody's out to get you, paranoia is just good thinking."
- Dr. Johnny Fever, WKRP