That's a damn good question that I've been asking myself for nearly three years. I can't answer that one but I can give a bit of vaguely relevant information. I like working in cartoon + line mode and I found that in that mode some figures I downloaded from the web had faces that were outlined in dots rather than lines. After about a year of investigation I have found that that is caused by the transparency maps applied to the lashes. This can be fixed by selecting lashes in the material box (obscured by your red line at top right) and then setting all the transparency sliders to zero. I know there aren't many perverts like me that like to work in cartoon + line mode, but maybe this will be of use to somebody. I hope you get an answer to your question as this whole area is one of puzzlement to me.