Okay, I had a chance to look at the website for the 100th BG to see what they have on the topic.
First, the label "Bloody Hundredth," as mentioned already, comes from high losses on some early missions, including Bremen and Munster in the same week in October 1943. And that was after heavy losses at Regensburg earlier. Stats show the 100th BG sustaining losses no greater than any other 8th AF group. Ten missions, however, do stand out with high losses in that group's history: August 17, 1943 - Regensburg, 9 lost; October 8, 1943 - Bremen, 7 lost; October 10, 1943 - Munster, 12 lost; March 6, 1944 - Berlin, 15 lost; May 24, 1944 - Berlin, 9 lost; July 29, 1944 - Merseburg, 8 lost; September 11, 1944 - Ruhland, 12 lost; and December 31, 1944 - Hamburg, 12 lost. No doubt each of those days were sad days for the group. The Munster raid was memorable as the group only put up 13 planes that day, and the plane that did make it back was piloted by Lt. Rosenthal, "Rosie," who at the time was a new replacement pilot to the group. (Rosie ended up becoming a legend himself for the group, flying two complete tours, plus then some, including being shot down and evading capture, plus serving as one of the lawyers for the Nuremberg trials; Rosie died only in this past year).
Second, the plane supposedly attributed to the famous wheels-down surrender shootout, known as "Picklepuss", aircraft #42 30063, was later found not to be the culprit. Both the pilot was interviewed, plus more significantly the GAF pilot involved in the shootdown of Picklepuss. As mentioned already about the Martin Middlebrook book, there was another plane that supposedly has this distinction. I haven't read Middlebrook's book, but a post I saw suggested it was a plane with the 390th BG, which was part of the same 13th Bomb Wing as the 100th BG. (Which is still too close for comfort, as the wing often flew mixed groups in the early years when individual groups couldn't put up enough planes. No doubt the 390th Bg similarly have records to suggest it wasn't them either.) [e.g.,
http://www.100thbg.com/mainpages/history/history3/org100th_11.htm]
So, no, the 100th BG was not singled out by the Luftwaffe.
Kevin Anderson