When I create those kinds of ads, the kinds that require example wordage, I throw a bit of humor into the mix. Subtle stuff. Nothing offensive, but enough that people should know it's only an example.

The key word there is “should.”

It doesn't always work. 

Case in point: There's a current classified ad letting potential customers know they can place a photo with their ad, thus letting readers see what they'd be purchasing. Alongside the example ad (accompanied by a photo of a generic car) I placed text-only ads. The text is semi-believable, but I made fun of the Ford Escort (of which I have proudly owned four), and its “classic styling” and faded blue paint job.

I also wrote “windows intact” as an inside joke. Years ago one of those Escorts I owned lost the driver's side window when I slammed the door. That's a story for another time, and quite hilarious on its own.

To add to the clarity that this was only an example ad, I gave each ad the News-Sentinel's main phone number.

What happened? People called. People wanted to purchase said nonexistent cars. 

So I am rewording the ad to be more an obvious example. Maybe one of the cars should be a Delorean with the capability to travel through time.