It's possible. Some of the things you were told were clearly incorrect (i.e. not being able to roam outside Germany). It could also be the issue of a language barrier. I could easily see a salesman wanting to err on the side of caution when it comes to expensive data roaming, as he doesn't want an angry customer complaining about an enormous bill or having their service shut off for lack of funds if he explained it incorrectly.

It could also just be ignorance about prepaid product offerings. I actually sold wireless service at the retail level while in college, and while I considered myself to be more knowledgeable than most other reps on postpaid plans, which constitute the majority of cell phone usage, I knew almost nothing about our prepaid service.