Depends on the game. Platformers and other gameplay focused games I often will since I'm there for the gameplay with the added sex. But VN types games I will of course read dialog for.
Wouldn't that just be porn then? if i have to skip dialogue because it is boring that probably means the "story" is not suited to me, so either read the text or just ditch the title.
For me it kind of depends on the game itself. I used to really enjoy visual novels, as in like. The Japanese ones when we'd get english translations. But a lot of the newer stuff I kinda of just skip through unless something catches my eye.
Never skip if I'm interested in the game. If the text isn't that good, I just unpack the files/unlock the gallery to look at all the art and call the game done.