Brake pads should be changed before there is any deterioration in braking performance.
If you had noticed a deterioration in braking performance you would probably have needed new discs as well as pads. Think of them the same as tyres - you replace tyres when they are worn so much that if they got any more worn you would have no grip in the wet. You do the same with brakes - you replace them before they wear so much that you would suddenly find yourself with ineffective brakes.
The only way you can tell if the pads have been replaced is to look at the thickness of friction material on the pads. You might have to take the wheel off to see this, depending on the design of wheel on your car.
If they are new you will have about 10 to 15 mm of friction material on each pad. If you were recommended to replace them, you probably only had somewhere between 2mm and 5mm of friction material left on the old pads.
In terms of feeling different new pads can actually feel slightly worse for the first20-50 miles until they are fully bedded in. The average new pad has a lining thickness of around 1/2", with disc brakes the friction between the pads and the discs produces' a considerable amount of heat, the thickness of the lining dissipates that to an extent. When your pads wear down to around a quarter of the original thickness changing them becomes imperative as they no longer have a thick enough friction material to dissipate the heat generated and in a worst case scenario, braking from speed could result in the pad material separating from the metal backing plate. No garage would say that they have changed the pads without doing so as the thickness of the lining can be seen without dismantling anything. You were not conned and you and your passengers are now a lot safer than you and they were!
You seem to misunderstand the need to replace brakes. They wear out. If you get to the stage where they feel different then they're long overdue for replacement.
New brake pads after bedding in should feel like the old ones.
Very likely
No. Brake linings wear down with use and have to be replaced when they get too thin. If they're not changed then they wear away to nothing and once this happens physical damage to the disks or drums can occur.
You should not notice any difference in the brake operation after they've been changed, although immediately after a change they can be LESS effective for a while until they've "bedded in".
What in the hell are you talking about?
but there was no deterioration in the brakes before the pads were replaced, if they were replaced? was conned?
