There are quite a number of all-white aircraft, of all types, around the world. Leasing companies generally give them out all white, and expect them back in the same condition, and as bookings at the aircraft paintshop can take a little while to organise you can find aircraft operating in this condition at the start or end of their service. Not spooky at all.

Some operators, especially charter/cargo ones, just do not bother to put markings on at all in the intervening time. However there will always be a registration, at the back of the aircraft.

Air Traffic control normally identify aircraft on the ground to other pilots by referring to its livery (eg "After the BA 747 passes taxi to gate 12") , and in these cases they use the expression "After the Whitetail 747 ....."

Here's another possibility. In this case it's just been acquired.

http://www.airliners.net/open.file/1046409/M/