Images of John Deere mower blades.
https://www.google.com/search?q=john+deere+mower+blades&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=-PXJUez2Iq6FyQHdj4HYDw&biw=1366&bih=617&sei=_PXJUda6JqPYyAHekIDYAQ
I'm having a problem seeing machinings that prevent putting the blade on the wrong way.
Personally, the only problem I have with Deere is the people they have out in the field.
I don't think it's Deere, I think they make fantastic lawn tractors, the one I bought was great.
It's the service that Deere depends on, it sucks and it sucks bad.
Back in 1975 my dad paid 5k for a 16 HP John Deere 300 riding lawn mower/tractor. That thing saved us all a lot of work. Then they started to cheapen up some of the models to compete with other brands.
We had all the attachments (all at additional cost), and when my parents sold their house, the tractor was sold in 2000 for $2500 with all the accessories. The guy that owns it, is still using it. We always kept it covered in the garage, it still looked new, with the exception of the tiller and mower deck. The Kohler engine ran like a dream.
All the John Deere dealerships in the area where I lived did very good work. But I am sure there are dealerships that suck also.
In the 90's John Deere started to farm out a lot of the work that the factories used to do, I knew a group that used to do the dealership prep for combines before they were delivered. They made pretty good money, but I am not sure they were all that good at what they were doing. They finished the assembly, tested the picker heads, etc.
If I needed a lawn tractor, if I ever have grass again, I would purchase a John Deere. Not much grass here in the Mojave desert.