Glidden makes high quality and low quality paint just like most well known manufacturers so it depends on which paint you are talking about. Ultra Hide is their low end line that they sell at Home Depot.

I got the Gripper primer at HD, they said I'd know right away (as soon as it dried) if it was going to adhere to the glossy 1970's paint (I did try to degloss/clean with TSP substitute but it still looked a little shiny to me). So far so good, it's been almost a week and mom says it's not peeling.

Glidden doesn't say which line they're giving away a quart from - just says "check color chips at Home Depot" - is that a bad sign?

Here is a link that might be useful: Glidden free quart

A good way I like to check adhesion is to find an inconspicuous spot and try to scrape some of the primer off with my fingernail. After a few hours, you should be able to scrape it off fairly easily, but the more it cures, the harder it should be to remove if it is truly stuck. You can also stick some tape on the primer and see if any primer comes off when you pull the tape off. If the primer hasn't peeled in a week, that's great, but really the true test is going to be when you apply a topcoat. The topcoat will stick to the primer and if the primer is not fully adhered, that will eventually pull hard enough on the primer so that all layers will peel.

The Glidden paint is Glidden 6000. It's new. You want 100 percent acrylic paint. They don't have specs for this product listed on their website yet so I can't tell if it is 100 percent acrylic or not. If it is a vinyl paint or some vinyl/acrylic mix, then I would call that medium to low quality....the best stuff is 100 percent acrylic these days.