Re: at wit's end
That's what I was thinking since a lot of the arms are now being made from stamped steel so they can vibrate and make noise, all my bikes that have the rigid alloy arms brake quietly all the time e but some of the newer ones that came with the stamped steel arms not only squeal but also have a more spongy feel to them since they also flex a little when brakes are applied hard. The alloy arms are more rigid so they have a better feel to them as well.
I've since switched to hydraulic disc brakes up front since I can get them cheap enough, these are a lot stronger than the mechanical disc brakes and always quiet. The last hydraulic caliper and lever setup costed me just over 30 on ebay and the extra stopping power is well worth it so I try to find bikes that already have a front disc brake if I can, but I've had a a lot better luck with the V brakes that have the more rigid alloy arms, they're quiet, they don't wear out the pads as quickly, and they will flip the bike if pulled on too hard...