[quote=@Hank]
<Snipped quote by GreivousKhan>

The only situation that stains a mercenary company's reputation is not obeying the contract. If the contract says to commit genocide, you commit genocide so hard Hitler would be proud. Refraining from committing said atrocity is what will stain your reputation. 
[/quote]

Well along those lines usually mercenaries that switch sides mid battle are the kind of things that can give a company a bad rep. You should check out the mercenary companies of Italy during the middle ages. 

Also you can say no to a contract, that won't give you bad rep, hard to agree to literal suicide in my mind...