Normal logic between guilds at least in Windia goes like this:
If you have a scammer in your guild and you take no action to removing that person, your guild is deemed a scammer guild because you guys support scammers.
If you remove the scammer and compensate for the amount scammed (if you vouched for the scammer, you compensate. If not, then no compensation is required) then your guild supports legitimacy.
It really does make your guild look bad if you don't compensate if the trade was a big trade involving many members of several guilds watching the trade.
If the trade was a small one-on-one scam, then compensation is usually not necessary since it may not have been the guild's fault. Compensation may still be good to give since the scam may have occurred because the scammer was using the guild's name to gain trust.
My statements ^ assume the amount of money scammed was huge vs a small amount without any vouchers used. Every situation can be different so I'm not gonna go into too much detail but the bottom line is:
The actions of one individual in the guild may not reflect the feelings of the whole entire guild.