What DIY paint are you using for your screen? Is it white or a gray? Is is regular paint or is it reflectively enhanced with a reflective paint?
How large is your screen?
How far away from the screen is the PJ?
A projected image should not look like a plasma TV, if it does you would get eye strain from viewing it long. A PJ should produce an image like you see in a good theater, but many times will actually be better than that.
A high gloss screen would hot spot like mad and not look like a plasma. The reason is that plasma TV's generate the image while a screen can only reflect the light that hits it.
The Sherwin-Williams ProClassic paint can make a decent screen, but a few people have had problems with it hot spotting for them.