I know when:

- When I'm taking bong hits, it takes 30 seconds for me to take my mouth away - sometimes I even drool.
- Red eye.
- Cottonmouth (only got it a few times, although the first time I smoked it was extremely bad).
- When beans on toast is the best food ever.
- Watching anything on TV is amazing.
- Sleepy.
- Deep thoughts/analytical mind.
- Giggles (only had this once).

That's for me, anyway. For some reason, music just sounds the same when I'm baked.