I brewed beer from kits and raw ingredients (malt, hops etc etc) for many years and when I saw your question I started to answer but as I type I realise I can't describe what you want to know. It depends in what way the hops were 'bad'. They generally add the 'bitter' flavour and bite so if they were old they might not impart that bitterness but add a bit of 'foostiness' - dusty, almost mouldy effect. I don't know about going off - do hops go off? I thought they had quite good preservative properties. Sorry, this doesn't really answer your question but it may provoke more knowledgable answers. Cheers, Andy