Cut and paste can be ok, for example, for the words of a song, or when some article isn't going to stick around reliably on the page you found it, or when you just want to give a passaage from something much longer.

But surely it's basic good manners not to present it in a way that might invite anyone to think it's something you wrote yourself, when it isn't.

After all, it doesn't take long to write "Here is something I found (here - with a link) and I thought it might interest/amuse/annoy Mudcatters."