Unfortunately, the PAD ban means this is one crack fountain you will be unable to drink from. (Which is, honestly, for the good, because the Andy-comes-out-scene was painful, and I don't mean that in the good "he captured the experience perfectly" way, and that's before you even get into the vague lesbian-as-predator undertones of the whole thing). But, in a nutshell, the post-Crisis Comet was a man who'd been mutated with horse DNA and had a lust-inducing aura, so despite... looking like a man who'd been mutated with horse DNA, Supergirl totally wanted to jump his bones from their first meeting. Until she found out he was actually a girl when he wasn't being Comet.
There were a lot of amazingly good things in the PAD Supergirl run. Comet was... kind of not one of them, on balance.