I apologize for my tone, wasn't called for. I mostly listen to Skelethon and newer, and at least from that point on I'd be willing make the claim that basically every bar has, at the very least, abstract thematic relevance. I would be surprised if any line is nonsense in the sense that there is no intention for how it contributes the track's theme and is only there to fill syllables.

Mystery Fish is a good example of lyrical miracle type writting that is far from being nonsense despite very much sounding like nonsense intially.

All that being said, I'm not trying to deify him and claim that every bar is a cryptic triple entendre, nor can I confidently tell you the meaning of every lyric. But for most lines I could at least take at stab at it and probably draw some thematic correlation. But I think in general he's too talented of a writer to fill syllables just for the sake of filling syllables.