A lot of random things including sprays can be transparent with transparent viewmodels on

[BeastyBoss-303]

also character outlines can cause the screen to darken and the outline to cover the players causing them to appear all (mostly) blue/all (mostly) red

[rbjaxter]

There's not really anything I can do about any of that unfortunately, that's just typically the nature of transparent viewmodels and how they apply their transparency. However if you used a different hud with transparent viewmodels and did not have the same problems, that'd be something I could look into. But historically they've always had some weird quirks to them