I just changed my plugs and found out two things. One is that something scares me and that the previous owner put the wrong plug into the engine. It would screw in but was way short on the spark end and too long on the wire end.
This is the one that was the wrong plug. It came out fine but was a little rusty.


This plug came out alot harder than the others. It came out with that gunk on it. The gunk wasn't on the tip, just on the part shown. What could this mean as far as problems?

 

The top one is what it is. It's been out in the environment a while and shows it.

The second one looks to have been running just a hare loose. That buildup is what happens when you form a "carbon seal" around an area that has been leaking a little. It's the difference between "contact" and "snug" with snug being the preferred torque...