Just ask people's opinion people! Its not that hard.
Find someone in the cafe that looks like they fit your target demographic and isn't too busy.
Put a smile on your face, walk up to them and say
"Hi ... my name is xxxx, I was wondering if you could help me figure out some possible problems with this business idea I've got.
And no ... I promise I'm not going to try to sell you anything"
Smile again.
Rinse, repeat and refine as necessary.
Find someone in the cafe that looks like they fit your target demographic and isn't too busy. Put a smile on your face, walk up to them and say
"Hi ... my name is xxxx, I was wondering if you could help me figure out some possible problems with this business idea I've got. And no ... I promise I'm not going to try to sell you anything"
Smile again. Rinse, repeat and refine as necessary.