Agreed.As others are saying, don't advertise!!! It really is that simple. If you are dumb enough to advertise you are dumb enough to 'sell' your ticket to anyone that offers the price you are asking without being too bothered whether they are likely to cause trouble or even support the away team!!
The truth is the club have an obligation to the membership groups to ensure tickets are sold in order of the priority set out at the time. If people have paid for a membership which entitles them to get tickets then they will be understandably aggrieved if others who haven't given that commitment are getting tickets from other sources. Where I agree with others is that there should be a better 'offiicial' ticket exchange. £25 rebate on next years season ticket with a limit of 6 occasions when you can do this (and no doubt you only get the rebate if your ticket is subsequently sold which, in view of the sell outs we're having, shouldn't be a problem).
And a system to non-ST holders to return tickets they can't use. That said, I am sure we've all bought tickets for events that, subsequently, we can't make. It happens.