I just noticed this poll changed XD
I used to watch it regularly a long time ago (first and second seasons), but then lost track of it due to it airing at different times on different channels that I couldn't keep track of. I caught a few episodes throughout Hoenn, though.
Now, with D&P, I only watch it either when I'm bored, or when I'm looking for specific episodes. The only episodes I'm truly interested in are the ones where something out of the ordinary happens (like catching a Pokemon, a Pokemon evolving, gym battles, major trainer battles (Paul), and even contests). I'm so sick of team rocket right now in the series that I sometimes change the channel when they attempt to steal someones Pokemon, and then change it back near the end of the episode once they're gone.
In general, I try to keep track of the major plot episodes, but that's it, really.