Sand -> No Substrate?

I've had my axolotl for about 3 months now. He's lived with a sand substrate for quite awhile, even at the store where I got him, and it's become a hassle to clean his poop and uneaten food.

To solve this, right before vacation, I emptied the sand from his tank. He still has some hidey holes and he appeared to be slipping all over the place.

Was this a bad idea?

Bare bottomed tanks are fine and are easy to clean. I think its a good move.

Ive often come across sites implying that bare bottom tanks (glass tanks that is) Can become stressful for your axolotl as they cannot grip the bottom of the tank due to the glass being so smooth and slippery. This isnt the case for plastic tanks as there texture isnt nearly as smooth and slippery as glass. Although ive never experienced any of this for myself, nor have I had experience with many axolotls and different substrates. this is where i got most of my information on :
Axolotls - Housing in Captivity
go to the section under the heading 'gravel, fine sand - substrates.'
Every axolotl is different though, you should just monitore him to see if he shows any sighn of struggle/stress.

It's important to remember that not everything on the internet is fact, and most of what we read relating to axolotls is considered opinion.

Many many people run bare bottomed tanks with really happy axies, many start, or end up, with bare bottomed around the edges (as axie like to move it away), and many just go all out with sand to begin with.

To be fair all axies are different, I have in the same tank one that swims to the surface, gulps air and swims around, burping out bubbles to regulate buoyancy and then another who when he does the same cannot easily get down.

Regarding cleaning of waste on sand, I've never seen this as being problematic, in fact axies have some of the easiest waste to clean, one big lump.

The key is not to let uneaten food or waste to build up, these things are a matter of daily maintenance and are important for water conditions, you'll have the same amount of both in a bare bottomed as in sand.

Incidentally I found when I switched to an earthworm staple diet that waste was more uniform and was never any uneaten food. Perhaps you could give that a try?