Basemetal has the reason: making forgery of low-cost
ancient coins is not a lucrative business (It was my point in the discussion about monneron's coins).
I am not so sure though about
his example with
Valens (to my estimate, this is already in
the
price range where forgers may have an interest).
Faking of uncleaned should be considered apart: it is cheeting rather than forgering.
However, we observe quite a lot of of 'good'
fakes on the market and even in the lower
price end. The problems is that many of them are made officially: for jewellery, as fillers
for collectors, museum copies, etc. Some
fakes of this kind are even honestly marked as
copies (but the mark can be removed). With a mass production such an activity is rentable.
Many of such
fakes, claimed to be genuine, arrived, finally, to the
ebay auctions. Luckily,
it seems that
selling them in a regular way it is not a profitable business: sellers are
spotted and they cannot sell
fakes for high prices. I have no comments whether the faking of
ancient coins is a popular addictive hobby.