Reasons for a professional name

I use pics from r/earthporn as filler images for test sites. This client loves the test image so much they'd like me to contact the original photographer and see if he'll sell them usage rights to the image.

"Oh sure!" I say, "I'm sure they'll be thrilled. Here, we can look it up right now."

We go to r/earthporn and I find the picture in minutes. The person's username is "TurdsMcpoopsalot*" My eyes widen. The bosses look at each other, wince, and look back at me.

"On second thought, we'll just go with the other stock image that you were telling us about."

Your username is seen by all sorts of people. Some whom you'd never even think of.

*I edited the username a little in an attempt to give ole' Turds some anonymity but, yes, that's essentially what it originally was.