c#

I know to never trust user input, since undesirable input could be compromise the application’s integrity in some way, be it accidental or intentional; however, is there a case for calling Page.IsValid even when no validation controls are on the page (again, I know its bad practice to be trusting user input by omitting validation)? Does Page.IsValid perform any other kinds of validation? I looked at MSDN, and the docs seem to suggest that Page.IsValid is only effective if there are validation controls on the page, or the Page.Validate method has been called. A friend of mine suggested that I always check Page.IsValid in the button click handlers every time even if there are no validation controls or explicit Page.Validate calls.