Dog crosses that don't work....

1) Terrier & Bulldog = Terribull ( a dog that makes awful mistakes)

2) Bloodhound & Labrador = Blabador ( a dog that barks incessantly)

3) Labrador Retriever + Curly Coated Retriever = Lab Coat Retriever, the choice of research scientists

and my favourite

4) Irish Water Spaniel + English Springer Spaniel = Irish Springer, a dog fresh and clean as a whistle