[rnln]

I do know a little about painting procedure. In fact, I paint parts of the car many times in the past, and paint whole car once with some helps. I mean a good paint job, not cheap spray and shiety look. Today, looking closely into the paint and cars while washing them, I have some questions. Let me describe my thought slowly...

1- My 911: I know this car has repaint on the front fenders in the past, probably when the PO did the slantnose conversion. The paint on these fenders are very good. They are shiny all the time. Sometimes, they get dirty but a normal wash and dry would make it look shiny. Usually, I am too lazy to polish them, because they won't benefit much from polish.

Doors and hoods are probably having the original paint. They are still straight and smooth but the look is so dull as an old car and if I don't polish them for a while, they will be a little sticky when I run my finger on them. If I polish them, the whole car will look the same, beautiful and shiny.

2- On our Lexus: the paint have been exceptionally good for years. I never have to polish it, just a normal wash would make the paint silky smooth. For years, it always felt smooth and slipery like there is a layer of something on the top and it has been like that for years. The Lexus didn't have sand buff, I can tell. A while ago, I had this Lexus to a body shop for the front hood minor repair and repaint. The guy did a super paint job with sand buff. It's look and feel better than new.

I have not washed my cars for a while. This morning, I realized the slippery layer is not there anymore, so I got down and did all cars wash and found the hood of my Lexus is almost sticky as my camry. Why is it not slippery anymore, even with the sand buff job? I checked the doors, they are still good. So that mean the PO owner really did something to the car to have that slipery fell. But what is it that stay on the car for so long (several years). If it's really what I thought, then that stuff is really supper.

3- The camry: after several weeks off the dealer lot, it's not shiny anymore, sticky, and I don't even feel like to wash it.

Questions:

I can conclude that... for long term, sand buff can make the paint look shiny/smooth but you still have to keep waxing/polishing it. Compound/polish/wax/etc, will make it smooth/silky/slipery but not for a long term. The max they can do is couple weeks, or month.
What is it that which keep the car smooth and slipery for years (or maybe forever?) as my Lexus was, and my 911's front fenders?

Another question I have is if it's ok to do some cheap repaint on some parts of my car like the doors. I am not ready for a whole car paint, and the paint is not that bad for that kind of job. I know that for a complete prof. paint job, you need minimum of prep, primer, color, and clear coat before sand buff, assumming the surface is very good. But what if I am cheap and don't want to spend too much time, can I just fine sand the door, then spray color, clear coat, and sand buff? As long as it look good or close to good. My question is will it stay for long and won't pill up or damage easily?

Note: "sticky" as "slightly rough", not slipery.