Cats Spraying everywhere!

My friend adopted 2 cats back in July and they were fine until about 2 wks after that. They started peeing everywhere.. The vet said it was not UTI. She has kept the litterboxes spotless. I mean they will go in there but they will still pee on the crapet and everything.. I said I would take them cuz she was going to take them to the shelter. But I don't want to to spray all over my house because I have other cats as well and I dont want them to start. Any suggestions on how I can help them not to pee all over my house? Theey are both neutered as well..

Some cats just spray. There are probably ways to help them and I am sure someone will eventually tell you. I suggest buying a Feliway Diffuser Plug-in. They are a bit expensive and so are the refills but they are worth it. Many people on here use them religiously.

Well they arrived her eabout an hour ago and have been using the litterbox just fine.. No spraying yet. *fingers Crossed*

You can get some Feliway spray too and everytiem they spray somewhere clean it up and then spray it with Feliway. It makes them think they have already sprayed there. You just have to keep reapplying it from time to time.

Two neutered males. Probably a little territory dispute in spite of the fact that they are both altered.
The feliway diffuser, as was mentioned, may prove effective given you follow the directions in regards to coverage per square foot.
The spray bottle feliway may work, but I've never tried using it to disguise urine smell as Solarity mentioned. Solarity, does that work?
I was under the impression that feliway mimics the scent produced by the scent glands in a cats cheeks and paw pads.

I have a senior (12 years old) female who insists on spraying and/or peeing at every doorway in my house, and in front of my kitchen sink. This is a relatively recent development. She has been ill and treated by the vet. My vet says it seems to be behavioral (she does also use the litterbox) and all I can really do is keep cleaning up after her and possibly consider restraining her, which I don't really have any place to do. I've been doing this (cleaning) and tried different sprays but they only work for so long. My husband is getting very upset with her and I am about at my wits end. Any other suggestions?
I should also note that the areas she's peeing on do not have carpet -- it is all tile, except for throw rugs/mats. I have read in another post about the rubber-backing, but only one or two of the areas in question qualify. The sprays I have tried say they work on all materials, but maybe someone can suggest something that is better for tile than the others.