It's not bad. Bad is unethical. We're not talking ethics here.
But it is potentially dangerous. To any number of people or projects.
Anything you present to a client is, of course, actually coming from your employer, and the clients know this. However, the clients are also aware that whatever you're presenting is also going to be interpreted to their customers as coming from them (if they do business with the software) or as coming from the client's management to its employees (if it's internal).
And that's the basis they judge it on. Either case can touch on sensitive issues (that you probably know nothing about), and being careless about names, or using sophomoric humor (like naming somebody Dilbert, for instance) is unlikely to endear one to the client, or to one's boss.