Yep they have always had lot of fans around the world, but I give u a small example of BVB Gloryhunters:
At the time of 11/12 CL there were no dortmund-fans at my hometown, just ManU and Chelsea and Barca fans. But things changed radically during the 12/13 season, and it's round of 16 phase. Almost all the chelsea and ManU fans were disappeared and there was a huge amount of sudden bvb-fans... I remember watching the final at a local bar with approx 70 ppl and I was the only Bayern supporter there. Rest of the mass were cheering for bvb... This is the reason I don't happen to like them, they got gloryhuntered pretty quickly.