Saying No for No Apparent Reason

Is telling your child “No” wrong if you have no other reason to say it other than just wanting to say it? Here is a better way to look at it. Your child asks you if they can watch a movie and you say “No” only because you just feel like not letting them. Is saying No for no reason acceptable?
Is that good parenting? Do you need more of a reason to say No other than the fact you simply just feel like saying No?

How can this backfire? Does it matter how old your child is, or should you always have a good reason for your decisions? Is there really the ability to say no for no other reason than to say no?

Maybe one of the following things are happening:
- Are you saying no because you are angry at something and feel like taking it out on your child?
- Are you saying no because you are lazy and don’t want to put the time in?
- Are you saying no because you simply have said yes too many times and you fear the child may be taking advantage of you?

I have always wondered what other parents thought about this. I have my theories but want to hear yours first.