I was "denied entry" into Russia but it was resolved without them actually sending me back to Vilnius (origin of my incoming flight) even though the airline had been contacted to make the arrangements.
My work visa said under nationality British, but I am American. My passport is, too, but I got the visa in London. Of course, the nationality was written in Russian which I didn't speak at the time so I didn't catch it. I spent about five hours in a glass cubicle with my luggage, watching all of the arrivals go by, and, more interestingly, the immigration agents. Not to go too OT, but...All female, all very stern, and all dressed in the very formal uniform - on top. Once the last pax had left they would all head to the break room showing me their glossy bright red high heels, fishnet stockings and uber-mini skirts! They left the breakroom door open (to keep an eye on me?) and I could see the Russian soap they were watching and hear them talk and laugh like teenagers and smoke like...well, like Russians. As soon as the next flight arrived, their stern faces returned and their legs would be safely hidden behind the immigration counter.
Finally they found the ONE man with the ONE ruler and the ONE pen that could be used to cross out "British" and write in "American" on my visa.