Mike Hartigan wrote:
When my home was built 15 years ago, there was some ugly taping on
the ceiling in the upstairs hallway. I pointed it out at the final
inspection, and it was 'repaired'. I'm now in the process of
painting and have decided to fix it 'correctly'. A bit of mud and a
little sanding should do it, but the ceiling has 2 coats of latex
paint that I'm aware of. Can I simply mud on top of the latex paint?
Or should I do some sort of surface preparation, first? Any other
considerations?

Joint compound will stick to glass until you scrape it off or it gets
wet. It'll certainly stick to the paint.

I'm waging a war against drywall sanding. Unless you gob the stuff on
there's little need to sand. Don't go into it expecting that you will
have to sand. You _can_ do it without sanding.

Use progressively thinner coats, scrape off the goobers and ridges
before the next coat, don't try to get it perfect on anything prior to
the last coat, and use a spray bottle in your other hand to spritz the
mud to keep it workable if it starts drying too fast.

R