I don't know of a way to make them enjoy their bath time but it can be made less stressful for them. I continually speak in a calm re-assuring tone of voice when bathing, make certain the water is at a consistent, nice warm temperature (not too hot though!), move slowly (fast movements seem to scare them). Some of the rescues I've fostered act afraid of the spray nozzle, so I try to limit it's use and keep it on the gentlest spray possible. It does get better, but some of mine never enjoy baths, they just tolerate them.
I've used Iv San Bernard products for almost two years now and have yet to find anything I like as well as their products. Their PEK conditioner is absolutely, hands down, the best hair conditioner -my Reno's long coat slips through my hands like silk pouring out of a faucet.
Iv San Bernard (USA & Canada), Fine Italian Pet Grooming Products and Equipment