Grease on bulb contacts
mihomes, you didn't explain why you grease them, but I've never heard of a bulb failing due to corrosion of a contact.
Grease is nonconductive, and if you get any on the glass envelope, that can cause hot-spots and premature failure. When handling halogen bulbs, for example, you are advised to not use bare fingers due to tiny amounts of skin oil getting onto the glass. It can't be good for ordinary incandescent bulbs either.
This is the first time I've seen this described. Did your father teach you to do it? Don't teach your sons.
If they didn't work before you checked them by pulling them out, then yes.
Not sure whom you are trying to insult by the statement but your comment:
"Did your father teach you to do it? Don't teach your sons
." would surely have insulted me.
In any case, everyone knows that grease, or most versions, are non-conductive but when you put grease on the base of a bulb it gets displaced by the contact pressure and doesn't cause a problem.
There are special greases, usually metallic-impregnated, used to improve high current connections, but that is not an issue here. If you have any question about that, look up the Trestle Project at Los Alamos or do a Google search on Magneform or ElMag. If you want to discus grease, high current contacts, etc., I am your man, just PM me and I will explain it to you.
The headlamps on most cars now run the halogen cycle to recover evaporated tungsten and do indeed run a hot envelope in order to re-cycle the tungsten that is evaporated from the hot filament. There are specific instructions on handling those bulbs and standard practice is to wipe them with alcohol and not touch them with fingers after they are clean.
If you want to protect your flashlight, the one that eventually dies in your car trunk, or a seldom-used strobe, a little grease on the contacts may save them from damage if the device gets wet or the batteries leak, and even "modern" alkaline batteries will leak at some point.
I hope you will have sufficent self integrity to apologize to the person you addressed in the statement quoted above.