It seems like they became enamored with US blues rock and hard psych and consciously decided to make an album in that style while scrapping any hint of the whimsical thoroughly British pop from the debut. Yeah I'm a sucker for the earlier style and generally lukewarm on the later style but the 2nd album would be less disappointing if the material wasn't so shoddy. Most if it's just boring and the Richie Havens cover is downright embarrassing.
Anyway, "Clean" is one of my favorite albums but I never feel like listening to the 2nd one. I'd say opener "Peace Loving Man" is the best cut on the album but TBH it's pretty stupid both musically and lyrically.