I think that some people who cannot positively identify an ingredient, they think there may be other things in the salad that they may not like, so they skip it over.
Your salad, to me, looks delicious, like something I would make. Personally, I may have loaded up on your salad and skipped other typical picnic dishes. I know people who will grab a scoop of food and pick out, say, the olives. Some people just do not like to experiment with trying different flavors.
Whenever I am unsure about something at a pot luck, I take one tablespoon on my plate to try it, then go back for more if I like it.
When I bring something to a pot luck dinner, I usually tape an index card with the ingredients on the side of the bowl.