I been have a hookup problem with these. I don't know if it's the hook or user flaw, but im only getting a good hookset on probably 1 out of 3 bites.

Any opinions on what it could be?

I use them quite a bit and have not had any trouble. How are you rigging the plastics on them; nose or wacky?

When I'm aware of a "take", I snug up against the fish and then side sweep set. Not a violent over head hook set like you'd do with an off-set worm hook.

wacky, and i'll have to try the sweep, what size would you recommend for a 4", i use 2/0

Make sure the weed guard is not below the barb, I was having trouble with these as well, until I noticed that was the way I was rigging them. To me it didn't seem like the guard would even stay closed above the barb, but it does. Another thing I did was up size my tackle a bit. Instead of using them on a ML rod w/6lb  Fluoro, I went to a M powered rod and 8lb, I am talking spinning gear. I have never had a problem with hook sets, regardless of where I placed the guard on casting gear. I also use the 2/0 w/4" senkos. For 5" senkos I use a different hook.

This is where i disagree with most everyone on here. most of the fisherman around here tend to agree with me.

for wacky rigging a 3" senko or similar i use a size 1 hook. a 1/0 for anything bigger.

you dont need a big hook for wacky rigging. plus the smaller the hook the slower the fall of the bait.

the sweep style hook set is very popular for this style. me i just take up the slack and SNAP. not too over powering mind you just a good snap.

For the 4" Senko, I'd recommend the size #1 or #1/0 at most. And I crimp down the barb.