Brake rotor replacement

So one of my rear brakes was making a noise and yadda-yadda. Long story short I ended up replacing both rear rotors and brake pads. After they were all done, the guy told me I should really get the front ones replaced too because they would wear the back ones down (making the $250 I just spent pointless). Is there any truth to this? I'm no expert but I examined all four rotors and I could visibly see the back ones were pretty bad which is why I only replaced them. Any advice?

And on a completely unrelated topic, is it true that using your air conditioning doesn't use more gas? My girlfriend said they did it on Mythbusters and they concluded using A/C does not use gas!

Thanks guys!! :D

p.s. I have a 2004 Pontiac Grand Am GT with front wheel drive... if that matters.

I think that guy was trying to upsell you. Your front brakes do 70% of the work when braking anyway so I don't see how the fronts would wear down the frears.

I'm no expert on AC (or much else for that matter) but since it runs on the power of the crank its taking power away from the engine requiring more effort for acceleration. In my mind that equates to more gas being used to power engine revolutions but I have no scientific proof to back that up

you only have to replace brake pads when they're worn. you rarely have to replace disks unless they're worn or the're not running true.

if the front pads are worn, reaplce them. if they're not worn, don't.

and the fronts actually take 75% of the braking.

A/C definitely effects fuel economy. Anything that makes the engine work harder will. The argument that is usually discussed is, with new cars being so aerodynamic, that at freeway speeds, you can have better mpg with the A/C on and windows closed than with A/C off and windows open.

Thanks for the replies, I think I'll save $250 and not give into his little warning about replacing the front ones. Thanks! :D