How do I know if my systems any good?

Ultimately, your ears will tell where the strengths and weakness are.

You could read professional reviews of your gear and see if you notice those details in your system.

As I get older I’ve modified my system to have a musical, inviting, and relaxing sound vs. ultimate detail and resolution.

You have to like the sound of your system day after day so adjust it to make yourself happy not comparing to a better system that day after day is not your cup of tea.

My 2¢

Honestly gauge it against a pair of headphones. Headphones are a good gut check to see how your room is too. Headphones have issues too like pad bounce in the cups that cause issue around 2k but most good ones are very good.

The best advice I have is to set up your speakers 2' away from you and listen that way.  If that sounds great but your listening location is not you need to think about your speaker placement and room.

Play this song when you power up your system...

"Here’s a little song I wrote
You might want to sing it note for note
Don’t worry, be happy
In every life we have some trouble…"

Bobby McFerrin

@emergingsoul -- "what are the things that should be considered when listening and judging an audio system..."

Seems like you are unnecessarily complicating things. The single overriding question to answer is: do you enjoy music when played on your system, or do you find yourself constantly wishing that it did something or another better?

Note the phrase "constantly wishing" -- due to the inconsistency of recordings, there will always be some tracks that may sound better on another setup.  However, if you like your system most of the time on a high percentage of your favorite music, consider your system "good." Your goal is to make yourself happy, not impress some other audiophile on an internet forum. 

Also note that many aspects of your existing system may be able to be improved for little or no cost. The position of speakers in a room can have a profound impact on imaging/soundstage and bass quality, so try moving things around a bit. Or, something like a throw rug on a bare floor can help. You don't always have to throw money at the latest audiophile fad to make things better.