Dry mouth can be an effect of how the juice is mixed, depending on where you buy it and what flavors you like. Tobacco flavors effect me this way the most. I've switched to flavors with menthol or citrus and it helped a lot.
E-Juice is comprised of 2 "base" food grade liquids, Propylene glycol and Vegetable Glycerin. In my opionion the best mix for new users is 50/50. Its less harsh on your throat. Some companies do change the ratios in order to achieve a diff result. which is perfectly safe but can ruin your vaping experience if not done correctly. Also check your expiration dates on your juices, they do have a shelf life and its important to use fresh juice.
If you shop at a local retailer, let them know what your experiencing they may have a better flavor/mix that will help.
Don't Give Up! Try some diff. Juices and give them a chance if you try one and "kinda like it" get small bottle and vape it for a week the flavors tend to warm to yah after a while.
Just a side note.....not sure what your hardware is but cheap starter kits can cause a bad experience, don't be afraid to upgrade a little.
50c is what, about 120F? That's not a bad temp for 10 minutes or so. Over that time frame it can do some odd stuff to some juice.
I've got a blueberry muffin recipe that sat in a car at about that temp for a whole day, it became a bitter caramel taste. And dark, darn near black. Nasty. It actually didn't have any impact on the Cuban cigar juice that was there too.