it's called cupping and we do it regularly. it's extremely easy to detect differences between coffees when tasting side by side. I roast my own at home, doing two batches of different coffees at a time, and try to compare them with each other as well as my previous batches. using grocery store coffee as a baseline is actually recommended as well.

I highly recommend doing a cupping sometime, it's great for learning what you like, you may discover something.