Kuhlis are not boring!!
I've had them for years and actually just got about 6 in today. They tend to be more visible when there are LOTS of hiding spaces around. I've also noticed they are better when dither fish are in the aquarium. Mine don't like to burrow as much as get under things like driftwood and rocks. I've seen them dig pretty far down in the sand looking for food but never to escape.
Also it's much easier to see yellow and black on white! Chesherica also has some striped kuhlies, and hers are much easier to spot in her pictures than my brown kuhlis on black sand.
Fishy, that is a really great shot of your kuhli in the leaf pile!