Yes they stink, no it doesn't get better, and flies suck. These are the issues that most people do not warn, or elaborate on. I would argue that the deep litter method is futile with these buggers. The rate at which they defecate quickly produced a layer of waste of the top later of chips. They do not scratch as ferociously as chickens which is essential for the ammonia to be turned within the chips.
As for flies, I've heard so many solutions, Vanilla Air Freshners--- didn't work, DE- doesn't keep flies from congregating around quail. The only conclusions I have been able to find is that keep the waste material far away from the quail if they are outside works best. This means putting them on raised wire. Also part of the problem of them being so messy and stinky is how they throw food every where and then defecate on top of it. Innovative feeders are essential.
I have yet to come up with a brooder set up for newly hatched chicks to 3 weeks of age that doesn't require constant cleaning and that doesn't stink.