Maybe get a shower head water filter? Slippery/slimy water is usually soft water, and sewer smell is just gross. Something like this might help. I didn't do a lot of research into what filter is best, that was just an example of what I'm talking about. Well water can have some seasonal variation, and a filter can keep those swings from screwing with your beauty routine.
I know these were around for a while: http://www.amazon.com/Jonathan-Product-Beauty-Shower-Purification/dp/B000PI13SU
Not sure if they work or not