I have a calibrated wide gamut monitor but, there are other layers of problems as well. The monitor itself maybe calibrated but not all application software, especially some of the most popular web browsers are not color profile aware. On top of it, lighting condition of the room can do a trick on human eyes. I'd imagine people serious enough to buy photographs would know about color management and have their equipment calibrated accordingly. For casual users, even quite a bit of color shift aren't even perceived. Heck, I didn't even know how off my colors were until I started editing photographs here and sending them to be printed by labs. (but that perhaps is off topic for this forum)