xcolor, Y U NO decent cyan?

And Magenta too – I tried to definecolor my own pure cyan and magenta in the obvious way and both are noticeably off (yellow too, if you look close). Is this a feature in the sense it will look more correct on a color printer this way (I couldn’t try yet, I haven’t one…) and I should not overwrite xcolor’s defaults? Even stranger is that I can’t spot a difference when it comes to red, green, blue. (Note that other "special" colors also aren’t necessarily that what you might expect.)

MWE (Minimum Working Eyesore, w/o packages)

begin{document}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
definecolor{test1}{rgb}{0,0,0}
definecolor{test2}{rgb}{0,0,255}
definecolor{test3}{rgb}{0,255,0}
definecolor{test4}{rgb}{0,255,255}
definecolor{test5}{rgb}{255,0,0}
definecolor{test6}{rgb}{255,0,255}
definecolor{test7}{rgb}{255,255,0}
definecolor{test8}{rgb}{255,255,255}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
noindent
textcolor{test2}{$bullet$} textcolor{blue}{$bullet$}
textcolor{test3}{$bullet$} textcolor{green}{$bullet$}
textcolor{test5}{$bullet$} textcolor{red}{$bullet$}
textcolor{test4}{$bullet$} textcolor{cyan}{$bullet$}
textcolor{test6}{$bullet$} textcolor{magenta}{$bullet$}
textcolor{test7}{$bullet$} textcolor{yellow}{$bullet$}

end{document}