My concern is bridging too. It’s an old photo and it would have had a vip pad as well but bridging was my main concern.
Looks like your saddle is bridging to me - hardly any sweat along the panels makes me think they're sitting off the horses back a bit and causing pressure points. On a positive it looks very symmetrical
Agree bridging. Was the VIP full length of saddle cloth? Or possibly short and going some way to explain pattern?
I think good sweat marks should run whole length of back.
I don't think this is necessarily a bad sweat pattern. Sometimes the pressured areas are the ones with no sweat. I suspect here is one of those times.
No, definitely not bridging. The lack of sweat almost anywhere under the saddle does concern me slightly, you'd normally see a fair bit of sweat under the rear of the saddle, but the pressure under the front can be enough to occlude sweat glands. Here it looks like the overall load, and especially to the rear of the saddle, may be preventing sweating.
Exactly, and this is usually the case, though everyone thinks it's bridging. Sweat patterns are not a great way to assess fit.
In this case I would say that the rider has more contact with the right leg, the saddle could be slipping to the left or the pad may not have been put on straight. That's about all I'd want to say categorically, there is no short cut to evaluating saddle fit, no matter what people say.
And as an addition the dirty areas are areas of movement, a slight lack of contact allowing the two surfaces to move against each other - the opposite of bridging. You would usually expect to see this around the edges, though I'd expect them to come a little more under the rear of the saddle. There is a big dirt patch under the flaps/rider's knees which might indicate an issue with the horse's shoulders and the saddle/rider's legs, but again it's hard to say.
I'm in awe you have been able to take so much from a sweaty saddle cloth!