Having had the dubious pleasure of working in a chicken factory and seeing the process and the amount of handling and then the cleaning regime that goes on every night I would say that in general it's ok NOT to wash a fresh bird ... but I still do give most birds a careful rinse under the cold tap because I don't know which factory the birds I buy in my local shops came from ... However, if bought from the factory shop, then no, I don't feel the need to rinse it under the tap, but, I do use the same professional cleaning solutions at home that I used to use in my snack bar when cleaning in my kitchen, but I'm pretty much (or certainly used to be) immune to the germs that abound in the chicken world ... You develop an immunity when you are handling the damn things, basically, everything gets covered in sh!t when you are moving chickens then you sit and have yer sarnies and tea after opening the curtains on your wagon etc.
It's the catchers I always felt for ... catching anything from 3,500 birds and up to around 7,000 per load (usually in about 45 minutes for 7,000 hens, or 20 odd minutes for 3,500 cocks) then back to their van for a cuppa, a fag and a packet of crisps or a sarnie, few of them bothered to wash their hands in between loads (they'd usually catch about 5 or 6 loads a shift.) Fit buggers they were ... out of boredom one day I decided to give them a hand (officially I was on a break for the tachograph) ... going at less than half the speed they go at, I was dying after just 10 minutes ... bend yourself double, grab a couple of birds legs in each hand and pass both handfuls to one hand then grab another few legs in empty hand, stand upright and step over to cages (baskets) and plop the birds in then repeat.
On average, at six weeks old the birds would weight enough that lifting them to chest height took a little effort, especially when holding 4 or 5 in one hand and 2 or 3 in the other ... the catchers can grab a lot more than that in one go, they can easily grab 5 or 6 birds in each hand ... they're not supposed to of course, but picking the birds up 2 at a time the wagons would never get loaded on schedule.