I understand that feeling. I had that the first time I went to a store as an absolute beginner to try out some basses in order to select my first bass.
I did return to try out a fretless bass after about 7 weeks of B2B lessons and felt a little better about playing in the store. What really helped was reviewing the 3 Beginner Bass Riffs (You Can’t F*** Up) video. Here is a link to the thread:
This, along with some B2B lessons, helped me feel better trying out the bass at the store. (No, I didn’t buy that bass that day. However, I do have another different fretless bass on back order that should arrive right around the time I complete B2B for the first time and it will be a gift to myself as sort of a graduation present along with a reason to repeat the course on a new bass.)