@browncoat - Well, they might be uncomfortable, just generally they are used to irrigate the bladder when the patient has a serious infection or something else wrong. And frankly, if you've ever had a serious bladder infection or a problem with your prostate you would be glad to have a catheter inserted in order to get rid of it.
It can honestly feel like you're passing broken glass, when you can get anything out at all. For a lot of people being able to pass water through the catheter is the first release they've had a long time.
It can be painful, but usually only when they are inserting it. Once it's in there it's not such a big deal. And a lot of people have to live with them, unfortunately, so they make the best of it.