Not recommended. A pin will 'float'... sometimes it might acquire a charge from internal capacitances and over a period of time you will read a High when earlier it was a Low.

Use internal Pull-Up's where available and pull down with a switch externally for minimum component count. Try not to wire +5v to things like Switches and Sensors... especially if that same +5v supplies your PIC or other Logic... all you're doing is asking for noise to be induced into your Power Supply circuits which could then cause you grief elsewhere.