Ok. Here is part of the truth. People think that:
A. Many BT’s are weird. A little off.
B. If you are a changing person, how is anyone to know how set you are in what you are doing now.
C. Some BT’s seem to be living in a different sort of world, where ideals replace realities. This is closely connected to A.
Popa being cynical:
A. Maybe your sincerity scares people off who aren’t as sincere.
B. Maybe people who do not see much worth in Judaism, and are only continuing to do what they have always done; don’t see anything in common with people who choose it willingly.
Now, I know what I am alleging is anecdotal,and I’m going to be yelled at. I can handle the yelling. The OP wanted to know what stereotype she is battling.