You have to look at the intent.
The aspect of altering photos that gets to me is when a photo is faked to be misleading. It can be done with or without photoshop.... like a news story about a car accident where children are hurt and someone throws a big stuffed animal into the scene to try to make it a tear-jerker.
If the altered picture is so silly as to be unbelievable, I can accept that it is in good fun, but not the sneaky ones that attempt to deceive.
For example, big storm and flooding hits New York... Photos start to appear like the shark swimming in the subway and on flooded streets.... those are attempts to deceive. The one of the Statue of Liberty hiding behind the pedestal as a huge wave crashes against it or the ones of Godzilla are obvious fakes with no intention to deceive.
If I took a moonlanding picture, added something to the image like a wire, and started to claim that it was proof that the moon landing was faked in a studio, that would be an attempt to deceive..... while Lucky the cat in the picture is obviously not.