PSA: Egg Coloring Glitch

I know that killing slime part, but the slime killing is way faster than slime drop looting. Anyway it's such a small deal that nobody abuses it lol...

Hadriel

It's not a big deal because there's no real way to abuse it.

First of all, the quest in question only gives 99,190 exp, which is half the amount you reported.
Since you have to kill 150 slimes, that's 661 extra experience per kill. Considering the fact that the map layout and spawn are pomegranate, you'd be better of grinding at pirates.

Of course, the "bonus exp" is cut off by the fact that, as you said, you can kill the required number of mobs way before you get the required number of drops.
That means either spending even more time killing to gather drops or magically finding a supplier who thought they could make a real business out of grinding those shitty mobs in hopes of selling their drops to people who have fooled themselves into believing they're netting amazing experience.