I'm pretty careful with what I buy, but failures happen.
Cantu Curling Cream. Though marketed to curly AND kinky hair.... Apparently my hair must be neither because this did nothing but make my hair greasy and dry. I use it to braid DH's hair. It's good for that, but not wash n gos.
Smooth n shine styling gel. My first buy. It was too thin and did nothing.
Far as out right fails that's all I can think of.