I honestly think that asking people to PAY for beta/alpha testing access is one of the core things wrong with today's games market. No one should pay to test a game, they should receive something for the effort they are willing to put into it. The more valid information (new bugs found) they submit the more they should get in return imho.
What effort? Beta testing isn't like it used to be where it was very structured and you had to apply for it like you would a job detailing your qualifications. Also you had to provide constant reports and keep a journal as well as required participation through board posting and interaction. It was really a lot of work and actually a good resume filler back in the day due to it.
Before companies started the paid early access/beta approach, beta had been degraded into nothing more than people using it as a means to test out a game before they bought it. You had numerous people who were technically illiterate making misleading comments, or unable to properly communicate a given issue. You had people farming for exploits (multi-player games mainly) to use to their advantage on release.
Lets be honest here though. All you are paying for is "early access". These days, for the most part... the bulk of bug finding is done by log programs they have running on peoples machines while playing in a beta. While is always helpful when someone finds and reports things, the idea that the "individual" is doing some major task is a bit of an exaggeration.