In the '90s, when an assistant professor at Hood College, I was visited by representatives of SCO trying to convince me that we should be running SCO UNIX in our labs. When I mentioned Linux (we had a couple slackware servers and a number of Ultrix machines at the time) to them, they looked at each other as if encountering a tremendously naive user. They then proceeded to belittle Linux. Later while still at Hood and then in industry I had occasions to talk with SCO representatives, and they consistently dealt with Linux with belittling rather than rational argument, similar to the way Microsoft now spreads FUD when discussing open source, so consistently that I couldn't help but suspect this was how they were told to deal with Linux.
SCO was a fine product at the time, and at the heart of a number of voice servers installed by Microlog in my time with that company, but the sales reps were incapable of delineating advantages or disadvantages of SCO vs. Linux.
Now I have trouble seeing someone who went with Linux rather than SCO in the '90s as viewing that as a mistake. SCO may not be dead, but they're no longer relevant.