That is true, WD40 and ACF50 do pick up the dirt and make it look very ratty, but underneath the metal is protected.
My bonnie looks like a sack of crap atm, but hopefully after a good scrub down with a bit of white spirit and soapy water she will look nearly as good as before, I say nearly because those down pipes get so hot the protective layer just burns right off!
In the end the rust on the downpipes got so bad last winter I had to make a choice, sand/polish it down, make em black, or leave it looking rather rusty. Take a look:
In the end I sanded them down and buffed them the best I could, but they look a bit dull which is something ill just have to live with cos I dont want em black or rusty, although I wouldnt say they look dreadful.
I know I shouldnt have let them get like that but last winter my bonnie was my only source of transport. Oh well!
Apart from that, ACF50 kept my chrome looking top notch, it is THE best product you can put on your chrome during the salty season! There are plenty of online shops based on ebay that sell it.
At the end of the day your level of corrosion will depend on if you are just a sunny sunday rider or an every day whatever the weather kind of rider, as well as the general climate you live in.
One final thing on my T100 I have found that the finish goes off quite quickly (as the pictures show) if your bike is used as a tool as well as a pleasure machine, there are so many nooks and crannies that need scrubbing but are just impossible to get to without taking things apart.