Helen - IMO these sorts of questionnaires aren't about trying to make you feel bad about yourself, they're there to give the team a good idea of your history and also to help you with the mental preparation for surgery by getting you to have an honest assessment of your eating habits.
Many of us who've got to this stage of needing surgery have lied to ourselves over the years - whether it's about what we eat, when we eat, the efforts we've made to change our lifestyles. A lot of us downplay, even to ourselves, what we've done. Because, lets face it, if were all eating healthy normal portions and doing the required exercise we wouldn't be morbidly obese.
Facing your demons is a good thing because surgery is NOT a magic bullet; it's a tool to help you lose weight but it still requires lifestyle changes or else, long term, the weight will go back on again and the surgery will have been for nowt.
So I wouldn't take it personally; the surgeon didn't wake up that morning and decide to compile a questionnaire specifically to humiliate you - they're way too busy for that and the fact that they're bariatric surgeons shows they recognise the issues obese people face and want to help them! I didn't get a written questionnaire but during my consultation the surgeon asked a lot of questions about previous diet attempts, my eating habits, my exercise regime etc.