What makes a good photo?

So you find yourself either looking at a photographer's work because you're looking to hire someone, you've received some pictures back from a photographer who took pictures at an event from you, or perhaps you find yourself reviewing your own pictures. So what exactly are you actually looking for? How do you know if a picture is actually any good? Well there is no real science.
You don't have to be a food critic to assess if you actually like the dish you've just been served at your local restaurant. But if you are going to spend money visiting a restaurant for a special occasion and might spend more than a 'casual' amount of money, that's when the views of a food critic might be useful. If you're going to spend money on a photographer, here is a list of things you might actually find useful to help you sift through the good and not so good photographers!
Most of us know a good picture when we see one, we just know it's a good picture, we don't necessarily know why it's a good picture, but we know it is. Well here is a way to break down your assessment under three common sense headings:
The Basics
This is the stuff that is not too difficult to identify but makes a huge difference on the final output
Focus - Is the main subject of the picture in focus? Or is all of it out of focus? Has the photographer tried to correct this by overcompensating in editing and the picture is a little grainy?
Exposure - is the picture to light? There are white spots with no picture detail there (signs of overexposure)? Or the picture looks like it's been whitewashed? Or is it too dark, and you struggle to make out defining lines, or see key pieces of picture
Basic Framing - Are the pictures all same-ish , i.e. Straight on, like a holiday picture? Or are their exciting positions from different photographic perspectives, e.g. Down at the eye level of a child, or over someone's shoulder, or peering through a bannister. Are some close ups, and others covering the entire 'scene'.
Sticking to brief - In situations where you have hired someone, did they stick to the brief that you gave them? If they didn't did they go beyond the brief and deliver an even better output? Or does it feel like they just did their own thing and didn't really listen to what you asked for?
The Technical 'Stuff'
This is the stuff that skilled photographers whip out to make their photos stand out from the crowd. It's stuff that happens both when they take the picture or during the editing process.
Lighting - is everything well light and balanced through the picture. If not is there a reason for it, do you think the photographer did it on purpose? Sometimes shadows are used in portraits to create dramatic effect.
Purposeful Framing - what else is in the picture? Is the background attractive or distracting? Is there unnecessary clutter or distracting expressions on faces of people in the background? Has the picture been cropped too much, to the point you can see graininess? Is there a purpose behind the view that the photographer has taken?
Editing - Has the picture had a filter applied - and if so does it actually work? Look for whether the picture is grainy, or has unwanted digital noise been removed? Also look out if there are any unwanted streaks of light coming into the picture. The Artistic Good 'Stuff'
Photography can be very subjective and emotive, even when just taking pictures of things or landscapes. Sometimes don't look at just one picture but the set, does it successfully convey a story? Does the photographer's work convey artistry? Do you get a sense of purpose behind the photographer's shots, and are even you surprised by some of the pictures?
I often find myself wondering 'How did they manage to catch that? Or who would have thought of taking a picture from there? Ultimately a great photographer makes you feel like you are in that place now, reliving a moment!
Well there you have it! Not too technical but hopefully useful enough to sharpen your eye as you begin to weed out the wheat from the chaff! I hope you find the right person! You know where we are ;)