There is a procedure to use white distilled vinegar in a mixture of 2:1 (4 gallons of vinegar to 2 gallons of water) to reduce the smell of sulfication in the water heater. Occasionally, there is a bacteria that gets in the water heater, sets up a "not too nice smell" and persists even though the water heater may be emptied, rinsed and refilled. The vinegar helps kill the bacteria and neutralize the sulfur that they produce. There is also a procedure to use clorox to do the same thing. Either way will remove the bacteria and their byproducts. You can look the process up at the following website:
http://beamalarm.com/Documents/atwoo...eshooting.html
or here:
http://www.atwoodmobile.com/manuals/...2011.19.07.pdf
One thing that I read last year (never paid attention to it before) is that RV antifreeze is extrememly corrosive to the anode rod. The recommendation was to leave the rod out of the water heater if you pour any antifreeze into the tank (to freezeproof the small bit of water left in the tank).
Hope this helps you some, but unless you've got a sulfur smell or taste, there's no need to use vinegar.