Pennywise (during their "sounds like Bad Religion" phase) does indeed sound like Bad Religion, but their lyrical work is crap. I actively dislike listening to them because they sound like Bad Religion but aren't good at what they do. They sound similar but go in the "pop shit" bucket while Bad Religion goes in the "good punk rock" bucket.
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Pandora can't quantify that sort of thing. They sound very similar but one of them is uninteresting-to-repellent. If I could find a music recommendation system that could, I'd pay it approximately all the money. As it is, Pandora is pretty crap; I can burn through my allotted skips in five minutes of listening because every station.
Hat-tip to a friend of mine who pointed this one out: Pandora also converges on the pop flavor of whatever genre you want to listen to. Industrial? I hope you like Nine Inch Nails. Synth/futurepop? New Order and Depeche Mode.