Where is the line between passionate and creepy?

I started out my career in the tech sector working in customer service for a small software company that made digital photography software. The job mostly consisted of answering e-mails and phone calls about how much the upgrade was and what new features were included.

At least once a day you’d get a call from THAT GUY (or gal, but usually it was a guy) who was irate about something the software did or did not do to his or her liking. THAT GUY would call and it would always involve a lot of swearing, exasperated sighs, and threats to either e-mail the CEO or call the better business bureau.

My fellow customer service reps and I would listen patiently and try to pass the ranter off to tech support as quickly as possible. “Sheesh,” I would think. “It’s only software.”

It wasn’t until I moved over to the marketing department that I started to understand the passion that software (or any product really) can generate in its users. Around that time I started working exclusively on the web, and turned into THAT GIRL.

Oh yes, I can’t deny it. I have been known to work myself up into a frothing rage when I have to deal with bad user experience . (and because I am THAT GIRL, blogs like Adobe UI Gripes totally float my boat).

However, there is a line between passionate and creepy. I’m not exactly sure how to define the line. As someone who has fired off an e-mail or two expressing my disappointment and frustration with some site or another, I’d like to think that’s totally on the right side of the line. People do that all the time, right?

I do know that the person who spit in Tech Crunch’s Michael Arrington’s face, crossed that line. In that post Arrington talks about some of the abuse he and his family have endured due to unhappy readers and just how crazy it is to get death threats over a blog:

I write about technology startups and news. In any sane world that shouldn’t make me someone who has to deal with death threats and being spat on. It shouldn’t require me to absorb more verbal abuse than a human being can realistically deal with.

We all can probably agree that physical harm and threatening death obliterates the line between passionate and creepy. But it’s still an interesting question to contemplate, what is the line between passionate and creepy? And how do you, as a consumer, express your displeasure when dealing with a shoddy experience, product, etc?