You can buy huge databases from other players, yes. They're full data sets, not "tainted," and have far more hands than have ever been played in the WSOP.

It's considered bad form in the poker world, and generally against site TOS, if you're a player using the data to have a read on a player before you've ever played him.

If you're just doing research, nobody cares at all. They might even give you the datasets, if they actually believe you. Or perhaps if you let them anonymize them?