Spotted...

The worse thing you can do is to assume that everyone have common sense!

It's just me really, I'm quite careful about selling bikes, before I do so I recommended them a certain lock, how to lock it, said that they should try strap etc. and 5 minutes worth of advice would make a difference, especially if it end up geting stolen within the first week!

I'm just being snobbery, ignore me.

Why should you care? I mean seriously, I don't give out a lecture or advice with every bike part I sell, if someone wants to buy something let them buy it and what they do with it afterwards is up to them, if he wants to be stupid and ride with no retention let him and all the other idots that do it do so, then when they crash and break their face they'll learn from their mistake :).