Before I do any painting, I always wash my models to rid them of finger oils etc so that the paint or primer will stick better. I usually use dawn dish soap or diluted Simple Green. The SG does a great job at getting rid of mold release agents and cleaning bare plastic or resin. It also rinses away much easier, but is definitely harsher than Dawn.
My latest model is a 1/32 Hasegawa Bf-109 F-2. I painted the cockpit using Vallejo and Tamiya paints, using Vallejo dullcote to seal everything in. For some dumb reason, I sprayed full strength SG on the assembled model to clean it before priming. The spray bottle of SG you buy at the store is still very concentrated and can be diluted further. As the model dried, I began to see that the SG had attacked the Vallejo dullcote and gave it a "frosted" look. Not completely white, but enough to change the finish and change the the look of the cockpit. I was able to rescue the cockpit using oil based filters and washes, which darkened it back up, but it s not as pretty as the original cockpit. I was soooooo proud of the original.
I don't know if this happened because I did not dilute the SG before using, or because SG and Vallejo(polyurethane) are not compatible at all. Most likely the later. I have never had problems using SG and enamels or lacquers. Can't remember if I have ever used it over Tamiya or other acrylics. Anyway... Just be careful if you use SG and acrylics of any kind. i will be using Sg only to clean bare plastic or resin from now on.
Obviously Dawn dish soap is very gentle and works on all paints without harm. It just takes more rinsing. Also, if you have a water softener in your home, that can leave some soap residue on the models. Think of how you feel in the shower. I always do a final rinse with filtered water from the RO system in the kitchen, kinda like a spot free rinse at the car wash.