I think the main reason you would want to refuse the breathalyzer, at least in the US, is so you won't have a DUI on your record, which looks very bad... But I'm not sure on this...
Yeah, you may be able to pull that off in the states, but in Canada, a refusal is an admission of guilt and will have the same repurcussions as if you had taken the test and failed.I have seen where the cops activley sit outside bars/establishments and you no sooner have the keys in the door, that they can demand that you submit to a breathalyser, regardless if you were stumbling to the car or "looked" like you were intoxicated.

The joke here in Halifax, for the Sailors, is everytime we came back from a looooong deployment and went ashore, guys would be stopped in broad daylight because the cops thought we were drunk, all it was, was we hadn't been ashore long enough to get our land legs, what I mean by that, is over a period of time and if the weather at sea is rough for a period of time, sailors learn to adapt with the roll of the ship, so if the swells and rolls are 30 to 40 ft and the ship is almost on it's side, well when your walking down the flats, it looks like your walking on the bulkhead, so your legs adapt to the motions of the sea..(just a little dit for you landlubbers)...sorry for being OT there.