When they are interested in good people who can code, not experience with their exact stack. That said, if I have experience with their stack, mentioning it may get me interested. Not requiring a CS degree. Mentioning being able to contribute back to open source is good.
Having entry level positions is a good thing, as long they don't require 2-3 years of work experience in your stack when you are hiring new grads. That's basically a red flag saying you want to find somebody who's cheap and not give them any training. But I definitely like if a company is hiring for a range of experience levels. If you are only hiring senior people, then where is the opportunity to grow in a position?
Jobs that want people who can do the job are preferably. If you only want people who have already done this exact job, you are asking people to move laterally, not up.
I love a description of common tasks that I would be expected to perform. I like to know how people communicate (multiple in person meetings everyday are a red flag though).
Having looked at my github code, or at least at the readme files, is nice. Don't ask me if I've ever done angular when I have an angular app on my resume with a working example. btw, I do Angular sure, but I don't respond to anything that requires photoshop skills.
Jobs that list how their interview process works make me happy.