I may as well admit that I do use one of those Pachmayer (overpriced inner tube sections) grip things on my P99, having felt the grip was just a little too slick and a little too small for my mitts. I really do like that extra width on the pistol grip.
That being said, these stick on things in the gunbroker ad are pretty lame looking and remind me vaguely of somebody cutting themselves up with a razor and having little bits of bloody toilet tissue stuck all over them.
I'd say the glue-on grip bits and the idiotic beavertail thing are a "no sale" around these parts.
Not to say that I think plasting small bits of them all over the P99 is attractive, functional, or necessary, but I have been known to use a bit of stair grip tape on guns now and then for extra grip. The p3at has a small strip on the front and back of the grip and I find it helps keep the gun from climbing out of my hand during recoil. Ymmv.
That picture reminds me of the cars that used to have the "black-out" lenses velcro'd to the tail & head lights. I don't know if they fall off, blow off, or are taken off due to legality, but the tell-tale velcro all over looks ridiculous.