The first time I ever set foot in Asia was last spring during our house hunting trip to KL. Prior to that I hadn't led a sheltered life, but it never occurred to me that a public restroom might not have an actual toilet. I didn't even realize that Asian toilets existed. Imagine my surprise then, walking into a bathroom in a nice, shiny, new mall in KL and opening the stall door only to be met by a hole in ground. I stood there transfixed for several minutes trying to figure out exactly how I was supposed to make it work and ended up deciding to just hold it. If only I had known then what I know now.
For starters, had I bothered to look in any of the other stalls I would have found the western toilet I was looking for. Outside of major urban areas all bets are off, but in KL if you are somewhere that there are multiple toilets catering to one gender your chances are very high that at least one of them will be a western toilet. Malls' toilets are usually half and half and like toilets are grouped together, so if you find yourself where I was, in a mall looking down at a hole in the ground that you're disinclined to use for whatever reason; check the stalls on the other side.
If, upon entering a bathroom, you see a large roll of toilet paper hanging on the wall make sure you take some. In my experience the existence of communal toilet paper by the sinks is a good indicator that there will not be any toilet paper in the stalls themselves. That being said, it's also not terribly uncommon for there to be no toilet paper in the bathroom at all. I've found it's best to always carry around one of the cardboard tubeless rolls of travel toilet paper that I unjustly mocked my mother for buying at Walmart prior to our trip to Malawi or a small pack of tissues so that you're never left in a jam.
It's not uncommon for the floor around the toilet to be soaking wet when the toilet isn't broken. There is a hose in every stall and people often rinse things out after use. I know it's supposed to be clean, but it still seems strange to me to have to choose between either rolling up your pants' legs or walking out of the bathroom with soaking wet ankles. If you are a woman it's infinitely easier if you're wearing a dress or a skirt, which you should probably do if you're traveling outside of KL and want to use a public restroom. Trust me on this.