When Does It Turn Creepy?

After avoiding the gym shower today because it was full of creepy old men trying to cop a glance, I wondered, "When does it cross the line from being an enjoyable experience of hot dudes showering together to creepy old men lurking around?"

Because if the shower this morning would have been full of the Men of Olympics 2008 (and gay ones who would have been interested in their surroundings), for example, I most likely wouldn't have returned to my locker to wait for the room to empty. So at what point, or age, does it become problematic? Is it even an age? Or, is it more in the behavior of the creepy old men? Then again, if the young, hot dudes would be acting in similar fashion, would I care?