Off the top of my head, you may have some sort of automasking activated on the brush. Have you tried resetting your brushes to their defaults? And is it happening on all meshes or just the mesh where you first noticed it?
i mean the brush automasking option not the mask by something options. cavity and backface masking are awesome.I have to try it in 3dcoat. can you paint the highpoly without uvs or will it need uvs? i really didn#t paint there in a long while.
What drag brush is? I had similar problems with stencil- 'pixelization', even with 2k map. Projection master is OK in some cases but most of the time I use simple 'dragrect' stroke and alpha or just stencil. And I always turn on automasking>backface mask. Show some screenshots.
In the picker palette, you could play around with some of the Orientation settings. Projection Master also has the option for having the strokes normalized to the surface. As for projecting through the model, you could try masking the back manually, or using a brush automask (backface and directional sound like helpful…
Making each turn a polygroup would help like cyrid said. You can do this easily in Max with material IDs as well. You can turn on BackFace Masking for brushes in Zbrush. Brush>AutoMasking>BackfaceMask This would help with sculping on the underside of the cloth.
Ah yeah,... go to the brush menu (top interface) and find AutoMasking, find the button 'Bsckface Masking' and press. This works with the brush but doesnt seem to work with the lasso. So if you have to use the lasso hide the other half of the mesh before you mask.
Cavity automasking would have gotten you something similar, but I think it's bugged in Z4 at the moment. You can workaround by using tool>masking>mask by cavity to mask off the recesses. Invert it for the opposite effect. There's a few brush settings that'll do something similar too, under brush>depth.
When I load my site, mozilla's scriptblocker autoblocks lightbox. I have multiple angles of my 3D stuff including 3D and wireframe. And the 2D section has multiple images. The thumbs are for projects. This is my favorite piece: http://rhkstudios.iseenothing.com/images/2D_battle_bun_final_2.jpg
In the smooth brush modifier under brush menu you can change the minimum number of connected edges. For other brushes I think you could look in the automasking subpallete, again under the brush menu. You can also use the mask subpallete in Tool menu and mask by borders and such.