Smut should exist as separate entries imo, but there's no reason why gen and shipping can't be combined. The majority of threads veer towards shipping anyway so everyone can put in their prefs whether they prefer gen or ship.

Now there are memes that don't really need to be separate entries. Smut/shipping pics and reverse smut/shipping pics can easily be combined; same applies to one-line and reverse one-line ship or smut; the picture memes exist as combo entries already and it seems to work fine. Alternatively gen text and picture text can be easily combined as suggested by anon above.

That said I'm against having a separate smut TFLN since people mix in smutty texts already so I don't really see the point in making an extra entry for that.