Keeping a Cat Off the Furniture?

The stairway is a definite "NOT GOING TO HAPPEN" nor should it!! Of course we don't like our cats being on our stove and our countertops and tables and maybe select furniture that we sit on all the time but to say the cat can't go in the stairway, it's ridiculous. MAYBE SHE SHOULD GET RID OF THE CAT IF SHE CAN'T HANDLE THE CAT WALKING ON HER FLOORS OR "STAIRWAY" THAT'S NO WAY FOR A ANIMAL TO LIVE. WHY DON'T SHE JUST KEEP IT IN A CAGE? (TOTAL SARCASM BY THE WAY)

Alright I'm sorry but this actually really bothers me. But for tips I don't know maybe she's not being consistent enough because the water does work pretty well... And eventually they just give up. It's possible she's not spending enough time with them and that's why they're acting out. To get her attention, like children whatever attention they can get they're going to keep doing that even if it's negitive. She needs to brush them a few minutes (about 3-5, depending on the length of hair)at least a few times a week. She won't notice the shedding as much on furniture after a week of brushing. I did notice some one in the comments before say use lemon or orange spray on the table tops. Of course spray it on paper and have something underneath it so it doesn't soak into the table. I've never tried it but supposedly they don't like the smell.
And I know how frustrating it is to have to clean your counters and stove down all the time before you eat or cook. So her wanting that to stop is very understandable. Does she have a tree for the cat to climb? Any Windows the cats can look out of? If not maybe she should rearrange her house so the cats can jump up and look out the windows.
I was having this issue with my cats and they have long hair. They would use the couch that we sat on all the time as their bed that they would sleep in all the time and it was getting disgusting. So I does innate two different chairs that they sit on. And because they seem to like to feel closeness to me so, I put one of my old shirts down on the chairs that I don't wear anymore and they have been loving it. Rarely do they ever get up on them spots that they used to lay all the time. Now I do let them jump up when I'm sitting down for them to sit on my lap to be petted or a short nap. But I personally still have issues with them jumping up on my counters and stove. It's only when I'm sleeping or gone because they know they're going to get sprayed with water lol little sh**'s! But sorry about the sarcasm, it's just the truth and the way that I feel. And maybe something she really needs to think about if she really wants cats.... Because they're just like us they have personalities and minds of Their Own and each and every single one of them are different. It's what makes them so special