I think some cycle paths can be well designed. I think it depends on who is using it partially. Cycle paths (long ones without lots of side roads) are great for the occasional cyclist, parent taking her kids out of a town/city, someone wanting a ride but not having to think about where they are going too much.
However sometimes the councils seems to think a cycle path is merely a case of painting a bit of the side of the road (doesn't have to be wide as cycles have such narrow tyres don't they), without thinking about it too much.
I think cycle paths are good (in general but aren't for everyone) because they get extra bums on saddles.
If I had powers on my council I would make it a condition of working in the road planning/resurfacing/engineering department that you had to cycle to work half the week so that they could appreciate the effect of their plans or workmanship
.