Interesting to see your post and I'm going to watch it rather than be any help to you!
I rescued an 18 month - 1 year male mongrel in September and he too at first was uninterested in other dogs, odd hellos seemed to go fine. He was then attacked twice by other dogs about 6 weeks in and it all changed. His appalling recall hasn't helped as he's on a long lead all the time.
However, although the attacks didn't help I do wonder whether this change would have happened anyway. From the very little I know of his history he was probably not well socialised when he came to us. I think he had a lot to learn about doggy etiquette and still does. We have discovered a lot about him in layers, sort of like peeling an onion over time. I do suspect that with everything so new and so overwhelming when he first arrived, other dogs were not high up his list of things to worry about or probably mine either. As he (and I) relaxed and settled down, that changed.
The other factor, I'm sure, is me. I was highly freaked out by the attacks and he subsequent snappiness with pretty much every dog he met afterwards. I don't think my nervousness has helped much especially as he's still attached to a lead - I modified a lot of my walking behaviour, much of it without really realising, like avoiding footpaths and favouring open fields where I could see other dogs more easily and avoid them. I also haul in the lead and move aside when I see another dog - yes I know I shouldn't but I can't face snapping and a tangled lead as well.
What I'm trying to do now is forget completely about the attacks or what he might have been like before and just treat him as a dog in need of socialisation. It's slow going but his interaction with dogs we meet regularly is now much much better, it's just all the others we have to worry about!
I shall await your replies from wiser owners with interest!
We rescued a 3-4 year old Springer spaniel Oct this year..then she came into season, cue lead walks for 4.5 weeks. Now been off lead for 8-9 weeks. In the house she is submissive, not allowed on furniture, crate trained, eats after us, not allowed up stairs etc, only greets people when invited, never jumps. Perfect!!
Up until now she has been good in park, on lead she shows little interest in other dogs but can say hello nicely, until last Thursday was the same off lead...into hedges, chasing birds etc. not particularly wanting to play with other dogs. Thurs she stopped to say hello to large lab, it became aggressive (apparently unusual for other dog) but I could call her off, happened again on Sunday, then again twice today.
She has at least 2 hours exercise per day, half of that is off lead pretty much flat out running/spanielling about.
Any advice (PS am single parent, lots of DC so have to walk her in busy places at least some of the time)