Funny you say this - I have had the same experience. I was at my father in laws and used his stud finder (Zircon) and ended up using my old Craftsman (about the same age as yours) and it worked much better !
I am still interested in the new Bosch (I have no ties to Bosch - I retired from the Auto Industry), as it can locate other items, but will keep the old Craftsman for sure.