Now sometimes VHLT doesn't do wonders... It tends to blend the lights in funny coloured gradients. It wasn't that noticeable in older tools I think.
You can see yellow>green>blue, it shouldn't be like that.
On your map, hlife_hotdog: not bad start! Currently it's a bit too simple I think, too repetitive, too clean. The lobby is a bit too open I think. Add few more objects or make it smaller. And again, try to make it dirtier. Don't be afraid of dirt. It's an underground facility built 50 years ago, the concrete should be runny, leaky and cracked in some places. Those lazy scientists wouldn't care about fixing it. Make some tiles cracked. Make few lamps not working or working pretty bad (glowing darker, yellowish or something). Make some wires hanging, some electric boxes and some other tiny shit.