Yes screenshot can be faked using photoshop and there are many scammers in localbitcoins that lure sellers with high market rate and scam others by fake screenshots.
Pff. I can even use microsoft paint for that.
Is it realy so easy to scam their arbitrators? Maybe there is any ways of showing the incoming transactions via skype screen show (or teamviewer, whatever)?
I already imagine how they are solving disputes about the f2f trades.