I was changing the spark plugs in my 94 fd. And the last shop that changed it put a Trailing spark plug where the Leading should've been. (two trailings)

(haven't pulled other two yet) and it had a little oil on the plug. The car hasn't been running for awhile and this find worried me. What should I do from here?

 

if the car has been modified then all trailings is common as an upgrade plug heat range.

unless the car is giving symptoms like burning oil or smoking ignore it and put the new plugs in and drive off into the sunset.