I picked an action that would be 1) super-common and 2) something
that every user should expect to be undo-able.
In one app, I did the thing and then chose Undo. It didn’t do
anything that I could see — the Undo command was available, but
had no visible effect. I did Undo again. No visible change. God
knows what was happening.
In the other app, Undo just wasn’t available. This is actually
better than a faulty Undo — but, still, it’s not good.
I poked around a little more, enough to find some additional bugs,
and then I trashed both apps. I deleted the account I had had to
create for the one app.
Window resizing (Brent’s other test for these two apps) and Undo support are good sniff tests. Undo especially, though — there’s nothing cosmetic about Undo support. It’s a red flag. You open a container of food and it smells foul, you throw it out. You try a new app and it doesn’t support Undo, you throw it out. And you empty the trash immediately in both cases. Get it out of the house.