There is a tipping point - the hundredth monkey - where knowledge passes into the collective consciousness and all members of the group acquire that knowledge.
@sainsburys bought a quiche yesterday at Cromwell Rd best before date is 5th March. Opened it today and it is covered in mould. Took it back today and was given a refund and it was just tossed in the bin by a staff member, not brought to the attention of a manager. Shameful.