Is it just a bad fit, are they noticibly better the more expensive options.
Yes. Well. Not necessarily super expensive.
Really cheap ones are just flat padding, these don’t conform to your arse. You want the ones that are 3D, and preferably have the padded spots under sit-bones and the lack of padding under your perineum. These can be had for say £30 or so these days. Also fit is important – they should be snug but comfortable, this keeps the pad snug to your arse and not moving about.
Lastly, you want to make sure that the main pads are in the right place. I have some great shorts that don’t sit right when I first put them on and need adjusting. This might mean pulling up higher at the back (esp if you have a big bum like me) and/or rotating the thighs inwards to allow the pad to move back.
It’s worth it though, I never ride without a pad unless I’m commuting, and for this reason my commuter has a cushy saddle.
On the subject of bibs – for me, they fit very well but after a while the straps get sweaty and uncomfortable, so I have recently been going back to non-bibs.