It's usually not worth their time, especially on wine/beer since the cost of duty is calculated on the actual amount of alcohol in the bottle - not the total liquid contents.

I had some jerk in Tijuana begin to lecture me that "You are only allowed one bottle of liquor" on a random questioning a while back. I had three bottles (didn't tell him they were Havana Club - still wrapped in newspaper in bags). I said "Actually, sir, it's not one bottle but 1 liter and I can bring back as much as I'd like as long as I pay the duty on the amount over the allowance. If you would like to prepare the paperwork I'd be more than happy to pay it". He huffed and just said "Just get out of here."

It's usually not worth their time to do the paperwork on that small amount of duty...