anything that was created to be sold, with
business efficiency in mind.

The quality will soons or later come to a level
thats can sustain on the market.

Its not that "professional quality" always means the highest available quality work.
There are also very high quality models etc,
wich I would not call professional, as
they took too much effort to make given their
market-value.

Portfolio Models of Artists are often themself not
"professional assets" but rather show the skill of the artist.
But if the Artist actually works on a paid project, he
will create assets of "lower" quality to meet the time contrains.