Ahhh the good old days. I'd have spreadsheets of when to cancel trial offers. Probably earned about $20-30k in electronics and cash overall during Freshman year in college.
Me and my roommates did this as well. We did it so much that one of my roommates actually got a legally threatening letter from on of the companies behind most of them (Trilegent I think it was) telling him to stop because he was abusing the system. Which was funny because they were so scammy to begin with.
Yikes. The worst I got was being sent to collections for a teeth whitening product that was designed to bill regardless of trial cancellation. I learned a ton about negotiating with customer service departments during this time too.