I'd say I'm on the same page as Sugar and Spice. I'm not about to go loaning my badge out to strangers, but I'm am secure enough in my own sisterhood to know that a shirt with my letters doesn't make them a sorority member.
Besides, when my chapter did party favors, we always put our letters on them. Most of our members ordered two favors, one for us, and one for our dates. A lot of times if I didn't want to babysit some guy at a date party, I'd bring a non-greek friend or a girlfriend from another sorority to a party. This was pretty commonplace on my campus.
Therefore, there were plenty of men and women with party-favor t-shirts or gifts on campus who weren't members. It never bothered me, I was just smart enough to know who was part of what chapter. And if someone made a total ass of themself at that party, I certainly wasn't going to give them a t-shirt.
This is just the way things were on my campus, I'm not saying this is right or wrong -- it's just the way it is. Different strokes for different folks
Don't judge others because they may or may not be more protective of their letters -- every GLO is different, and every campus is different. Just because you are more or less protective, doesn't make you a better member than someone else on this board.