1. There is no DHV in there.
2. You gave something that will only work if she says she's a vegetarian you didn't give any ways of making it variable depending on her interest.
3. By jumping straight to "I couldn't date a..." you have made it perfectly obvious that you are wanting to date her and blown yourself away.
I'm glad you brought up this point so I can clarify further.
Pt 1 - the DHV is showing you respect peoples beleifs / skills / values and you are not afraid to voice your own.
Pt 2 - if you can't improvise a little there is no hope is there.
Pt 3 - The way it is said is the most important thing. When I say "I wouldn't date a vegetarain, we would starve to death hahah, etc" it is like I am referring to "the people I would consider potential dates" ie not necessarily the girl I am talking to.....
I hope this is more clear.
.......and it bagged me an HB8 so I'm not complaining.