Paddy only did this a little bit - not a chewer much at all really - more of a nibbler.
I tried the bitter apple spray and he didn't love it, but it wasn't 100% fool-proof either. I ended up teaching him the "leave" command - started with a treat in my palm and as he moved his nose towards it, I closed my hand and said "leave". Then started saying "leave" without closing my hand and he got the idea - wait and keep your snout, out - and you get clicked and get the treat. Then I extended "leave" to other things, always "click and treating" when he did it. worked with stolen socks, furniture and soon (we were soooo lucky with Pads) he was beyond that stage and hasn't chewed since.
Other things I've read/been told:
Friend with two Springers (siblings from same litter) had them swiping food and chewing things - so put Colman's English mustard onto table and chair legs, plus made two sandwiches of Colman's English mustard and left one each on the side of the table. Walked out - each dog swiped a sandwich, gobbled it down - and consumed a large quantity of water. And never stole another piece of food. Meanwhile - smell of mustard on the furniture sent them running for cover. Can't vouch for how kind it is to your dog though....I can vouch for the fact that Chilli Sauce smeared onto the post of my bird food table put paid to thieving squirrels and man, was that funny to watch. They run up to the post, start up it then sniff and leg it. RESULT!
I think Gwen Bailey in "The Perfect Puppy" advocates getting a water pistol - squirt them but she says two key elements, IIRC:
1. you have to squirt immediately BEFORE they start to chew - if they've even got their gobs around the chew item, don't squirt just interrupt; and
2. you must do it so that they don't know that the squirting originates from you - otherwise they just learn not to do it when you're around. If they don't see where it comes from (you hide or you hide the water pistol), they think it's something to do with the piece of furniture, so don't do it whether you're there or not. Never tried it so can't vouch for it.
Denise