Below 10.000 is Low Res

Between 10 and 20 K medium Res

Between 20 and 40K High Res

Anything above 40 K is Pollution.

Normally the problem starts with the modelling.They model Low Res , then start subdeviding, but never clear out the extra mess it creates.

So you get a medium Res body with 50.000 poly mouths, or 10.000 poly ears, navels etc.
Mouth that will mostly be closed tot slight open. Ears that will mostly be covered with hair.

HIGH poly is not justified in the way it is used right now.

It has t have body, muscle and bone topology, or it can better be done with a displacement map.

My 2 cents.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!