Hexxus' musical number Toxic Love seems at first like just a reference to Hexxus' corruption and an excuse for Tim Curryto sing a sexy song in a kids' movienote though the movie version of "Toxic Love" was toned down — though not by much — in comparison to the uncut version that exists on the "songs used or inspired by the movie" soundtrack, but think about it: Hexxus is the embodiment of pollution. During the entire course of the song, he's helping the Leveler create smog and sludge - i.e. creating more pollution. If Hexxus is pollution, and he's creating more pollution... that means he's reproducing. Polluting nature is his version of sex! No wonder he seems so horny!
While on the subject of Hexxus, you have to wonder about his One-Winged Angel bit after the Leveler was shut off. It at first seems to kill him by cutting off the smog he was feeding from (Being a giant sentient smog cloud at the time). But then think back to what he started as. Oil. He even became a black skeleton before the smoke form at the start of Toxic Love. When the smog was gone with the engine turned off, Hexxus decided to go for the source. The oil and gas still in the Leveler.
In his rap, Batty mentions several disturbing things the humans supposedly did to him. In particular, he says he was "vivisectified." A vivisection is when you disect an animal while it's still alive, which would explain why he has wires beneath his skin.