Kitty pee problems

I recently had a friend ask me for help with a cat issue. It's a pretty common one, so I want to post this to help out others with the same problems.

Hey, I'm writing for my roommate who's having cat pee issues to see if you have any ideas. He has an 8-year-old male cat that's peeing on my friend's bed constantly. He never did this at my friend's old apartment, but he didn't start until 6 months after we moved, so it's not moving stress. He has a history of liver problems (doubt that's relevant). We brought him to the vet, who prescribed antibiotics for a bladder infection (10 days of something) but that didn't take care of it, so not sure it's that. He only pees in the one spot on my friend's bed and he obviously washes the comforter every time it happens. He's had it with this cat, so I'm trying to see what it could possibly be! Thanks. :/

My response:
First: Rule out physical causes
Get the vet to take a urine sample (with a needle) and check it for bacteria, blood cells, and/or crystals. Rule out physical causes. Sometimes a cat will urinate inappropriately because they do not feel physically well, and engage in litterbox avoidance. Once the urine is checked, the vet will be able to prescribe special foods or medications to help; kitty may still pee on the comforter while he isn't feeling well. (Note: If he DOES have bladder/urinary tract issues, get some Glycoflex to give him daily, as it has helped my ex's cat immensely with her interstitial cystitis).

Second: Get that odor OUT.
Cats can smell even the faintest traces of urine. Get your hands on Simple Solution Cat Odor Remover--not the regular stuff, but the cat specific kind. And then:
1. Launder the comforter, then spray the peed on area with the Simple Solution, let it sit for about half an hour, and launder again (don't bother drying inbetween washes)

2. Do the same for the sheet beneath the comforter.

3. Use the spray on the MATTRESS too, liberally on and around the spot. The odor penetrates through, so he's probably still smelling it there. Let it sit for about fifteen minutes, and then blot as much as you can with a towel. Repeat once, and then set a fan blowing over the top of the mattress to dry it out. IF you have a steam cleaner (they are indispensable here), use the upholstery attachment to clean the mattress area both before AND after the Simple Solution treatments. If you don't have one, see if you can borrow one, or rent one.

Third: Replace the "territory" pheromone with a "calming" one
Get your paws on a bottle of Feliway spray. It's expensive, but it WORKS. Spray the mattress with ONE squirt on the spot where kitty pees. Then spray the comforter as well, again ONE squirt. Do this once every day for a week, then space it out to every other day, then two days in between...then go down to once a week.

Fourth: Figure out non-physical causes
Now, if kitty does not have any physical issues? Try to sort out what may be stressing him. What's changed? Is there a new smell or sound in the house? New animal? New person coming over? If you need help figuring this out, after physical health problems are ruled out, we can chat and come up with what it might be. If you think you know what it is, let me know and I'll tell you the strategies I know for dealing with different stressors. If the cat is experiencing anxiety issues, and the cause cannot be found or eliminated, anxiety medications are actually very useful in helping with inappropriate urination behaviors.

I also recommend, for strategies in solving cat behavior problems, the following book by Dr. Nicholas Dodman:
The Cat Who Cried for Help: Attitudes, Emotions, and the Psychology of Cats