My personal theory on making a cube as hard to solve as possible
is as follows: Put the cube in
some very complex pretty, regular, pattern, such as the Plummer's
Cross with centers trebly rotated, or the Pons Asinorum on that
which looks like the simple Pons: the challenged cubemeister
will INVARIABLY say, "Oh,
this, this is just one of those and solved like this" and go through
a long hairy procedure, hopefully the wrong one,
or make an error, or try hard at understanding it, and so forth.
In short, s/he will take MORE time trying to undo what s/he perceives
as a "simple" hairy hack than a straightforward application of
solve-from-random technology.