Scavenging allows you to acquire goods in exchange for a little of your time. Quite often scavenging can offer you a better return for your money/time than buying shop bought goods.
The quality of the garbage that you can recover depends on the quality of the garbage being thrown away. If you live in, or can get access to, a wealthy middle class city, then your pickings will be a lot better than from a poor town. For instance one municipal/public recycling depot near to where I live has a constant supply of near-new printers and other computer components, all thrown into the skip for landfill. That's how much wealth is just being tossed away. It's remarkable when you think about it. Anyway, it's the same thing at the car boot sale at lunch time when they all pack up their fold-out table and go home: a melange of unsold goods dumped by the nearby rubbish bins because the owners don't want them anymore.
Don't worry about the stigma of sifting through garbage; you're the one that benefits by it. If you spend half an hour scavenging for a bag full of items that would cost 2 or more hours of labour then you've made a decent saving. Also don’t worry that it’s just part of a passing fad that SWPL or trendy MC’s do, because I’ve seen working class people do it as well.
You should be aware of the legal implications before hand though. It seems that sifting through refuse can get you into trouble (theft, destruction of property, trespassing etc), so if you’re interested but don’t want to get nicked, then stick to bins on public property or ask the store manager and/or security staff before hand.
JD, a freegan, says almost everybody who shares his lifestyle will have encountered security personnel during foraging escapades. He says: “I have personally encountered a number of threats from store managers and the occasional policeman.
A few links (or just put the related terms into a search engine):