You probably need to come and stand next to me when horses go round the paddock!!
I find it very worthwhile looking at them and sometimes a horse will jump out. It's why I can back plenty of winners when I am point to pointing especially early in the season. In fact on Sunday I went to Buckfastleigh point to point and spotted a horse in the paddock that looked awful. It was like an emaciated greyhound and walked round with its head on the floor. Yet because of who trained it, it was odds-on favourite. I went to speak to my bookie and said no way will that win. So he pushed the price right out and punters steamed in. It lead from flag fall and I was quietly bricking it but it stopped with two to jump and could hardly raise a canter. Bookie was well happy and gave me two free bets (both of which then duly won!)
I think you need to look at the condition of the coat primarily. If it looks shiny (the shinier the better) the horse is well. If the coat appears to have "dapples" on the neck and down the hind quarters - its super well. You should be able to see some ribs (about 4 or 5 but no more) and there is often a line that appears along the bottom of the stomach when the horse is really fit. It should look muscular but not fat. Look as the horse is walking away from you and it should have good definition of the muscles down the bottom by the tail. If its a little "sloppy" in its musculature, then its unlikely to be fit enough yet.
