Clone Armies in Trek

Considering how easy it is to create clones in the Trek Universe, what
is to stop some power-hungry megalomaniac like Khan or Lore from
manufacturing clone armies, given if someone had the proper resources
and facilities?  It is already known that the Dominion creates their
Jem'hadar armies from a clone-like process.  Of course, if I was a
megalomaniac wanting to take on the Federation I would create clone
armies, with equipment and technology acquired through the black
market, in secrecy on some remote planet that the Feds would hardly
notice.