Is buying a car that had a head gasket replaced sorta like buying salvaged?
 

In that the engine won't be the same again? And should a car that at one point overheated and then repaired (new HG) be priced half of what it's worth like how salvaged-titled cars are?

No. If the repair was done properly the car is better than it was before. I'd want to make sure the head was sent off and tested, but otherwise it would be a selling point to me.

When people are shopping for an M103-104 engine they're hoping the head gasket has been done.

When people are shopping for a 603 diesel they're hoping its had a new headgasket and the original number 14 head replaced.

When people buy a higher mileage vintage V8 Mercedes, they're hoping its had a valve job at some point.

Get the trend?

That statements doubly false. There are plenty piece of you know what clean title cars, and plenty of really nice salvage cars. My 300D is salvage and you wouldn't be able to figure out it was wrecked unless I showed you the title.

Headgasket doesn't detract from the value IMO, especially if its a car like an M104 Benz where its inevitable. I'd be happy to hear one had been done recently.

No it won't ever be the same. Why would you want the same? I'd want better.

If it overheated, it isn't good. If you overheated it, I don't care how many head gaskets you replace, I don't want it.