i'm all for using the Q-tip. I don't think you'll remove the stains, though. They will stay as history of what the card was glued to. I often see cards with circular glue stains and assume it was glued to a scrapbook at one time or another. The fact that it doesn't have paper remnants doesn't make me think one thing or another. On the other hand, I just bought a Tarzan bread card that was clearly pulled from a scrapbook and has a spot of paperloss. So, we have the 4 various states of scrapbook cards:
1. no evidence
2. glue but no paper
3. glue and paper
4. paperloss
It brings up another question though, what percentage of prewar cards do you think were glued into a scrapbook at one time? I'm going to throw out a guess of 10%.
Nice card by the way