Hmm, I played around with one of those at Yodabashi the other day and it seemed fine. Did a quick search for some reviews [1] and none of them mention anything about the touchscreen being bad - seems like a standard 5-finger capacitive multitouch. I wonder if you just've just had bad luck. I searched for "bad" and "terrible" touchscreen and didn't find any results. If it was something widespread, it'd be all over the Android forums.

[1] https://www.google.com/#q=sharp+aquos+crystal+review