In my experience, cats do not like to be dressed up. None of the cats I know or have known have enjoyed being wrapped up in a blanket, wearing sweaters or anything similar. Then I saw a cat of a friend wearing a sweater the other day! It turned out that the cat had to be shaved due to a bunch of clumps forming in its fur (I totally understand; I have a long-hair who gets like that!) and it was wearing the sweater to stay warm.
I have also seen costumes for cats and thought, "What cat would be caught dead wearing one of those?" It turns out that some cats really don't mind! It can be really cute, too. While I would neve advocate dressing up a cat who doesn't enjoy it, if it doesn't mind... I suppose there's no harm.
Do you dress up your pets for Halloween? Tell us what they wear in the chat!