Yes Joe, they weren't the strongest hook on the market were they!
I had a size 6 open out on a splasher when I was chub fishing on the Wey, they were consigned to the bin.
Going back further in time, a group of us were at the start of a 6 day stint on the Avon and most of us stocked up on Drennan Specialist 10's for caster work in a local shop.
We'd all been using them for a while without any problems. By the Tuesday however, 3 of us had lost barbel due to the hooks opening out. After comparing notes in the pub that evening it was unanimously agreed to return them to the shop the next morning! Obviously a bad batch.
Lots of good hooks available now though, ... I have used Fox Armor for years in 10's without a problem as well as ESP Raptor T7 in 8s and 9s which are my other favourites, got to look for a replacement soon since the Raptors have been discontinued of course.