At what point is the patina of an antique weapon considered ruined?
I see antique guns in all kinds of conditions, some haven't had any work done to them and others are polished to near "perfection".
I'm quite new in this business and I'd like to learn how to spot the pieces that are worth collecting and the ones that are not.

I was recently offered a wheellock pistol, as such:
http://i.imgur.com/SNEtW.jpg

My non-existent experience however thought the surface looks overly wire-brushed and I didn't buy it just in case.

Mikko:
You ask an important question. Here's a thread I started on this topic, not about guns per se, but applicable. Antique guns are not a prime interest of mine, but there are many here who can certainly weigh in on this. As well, there are other threads here on patinas.

'Patinas: Leave them alone? When to clean? ... etc.'
http://www.myArmoury.com/talk/viewtopic.php?t=25568

Welcome.

Jon

Well, I'm not commenting on this item specifically because it's presumably still for sale.

But if you want to talk generally about the removal of patina etc, then I've often thought that sometimes the problem is 'general' dealers with a basic knowledge of a broad range of items apply a 'quickest is best' and 'one size fits all' approach to quickly 'cleaning' their new acquisitions for immediate resale.
Whether it's removing patina or repairing damage or 'bringing out' the pattern welding or wootz with ugly overp0lishing and incorrect etching.
Enthusiasm for quick profit often outweighs specialist knowledge or care and respect for the item.
Look at the plethora of overp0lished antique blades flooding out of India at the moment. All reground and repolished to a high sheen, etched in the hope of finding fine wootz, but usually just showing their lamination and then often incorrectly described as 'pattern welded' and sold to western collectors.