Considering the following scenario:
After deployment of SegWit, there remain two old clients (with software that is unaware of SegWit) A & B.
A funds a transaction to pay B using a SegWit output which appears to both as
Upgraded nodes ignore this transaction, as it obviously isn't signed correctly under the rules of SegWit. (Perhaps even ban old nodes that relay this "invalid transaction" to them?) However, among old nodes the transaction gets propagated as valid.
In the case that B gets notice of the transaction, would it display an "incoming unconfirmed transaction"?
Could people get fooled that way if they accept Zero Confirmation (which I'm aware isn't safe)?