Yes this is quite common (No pictures until you purchase)... but Im hoping the other more secretive behavior is only happening in some stores in the States and isnt the case in Canadian stores! I want to be able to try on a dress or two with my mom as she lives in Vancouver.. but I have no intentions of buying it there!
What about doing that and telling them you're from the other end of the country, so can't buy your dress in vancouver but if you settle on one to purchase you want to know what it is. Sometimes they'll write down on a little card for you what the dress style is. I've had that done for me.