Well regular soldiers also get hired to do that, the big difference is the employer, as a regular soldier you're employed by the state, as a mercenary by a private entity.
In war they are more or less treated the same under the law, they're counted as regular combatants.
Mercenary business is always at least a little shady, since they often get used for shady stuff.
Oh I was merely expanding a little on that yes, we are in agreement;) I commented before my first coffee, so my phrasing could've been better.