OK I'll admit to having given up reading after page 4! Slow weekend on the forums, weather too crap to get out (lovely up here in NE Scotland)?
I'm a dog walker, a hill walker, a cyclist and do a bit of running too. When I'm out with the dog (Black Lab) she's off the lead 90% of the time as she's generally well behaved and it's better exercise/more fun for her. Although we live in a fairly rural setting a lot of the tracks, paths etc we use are also well used by others too. If I'm out with the dog I'll bring her under control around cyclists, joggers, walkers, families (especially with young kids), other dogs etc. It doesn't ruin the dogs walk, its courteous and it's safer for all involved. It's nice to be thanked, but I don't expect it.
When I'm out with the bike, jogging or even just walking and someone brings their dog under control to let me past then I always thank them. Just the same as I do if someone without a dog moves to the side to let me past because I'm moving faster. If I'm on the bike I'll slow down to almost walking speed when passing too, and stop if I need to. It's not uncommon for me to stop to say 'hi' to a dog, especially young ones, to show that the strange beast on two wheels isn't something to be chased or barked at.
Maybe I'm lucky in where I live but if I want to get out on the bike and avoid people/dogs I've got plenty of choice of places to go, even if it may then involve either a longer ride or sticking the bike on the car for a bit.
It cost us nothing to be courteous and helps stave off the "bloody cyclists", "irresponsible dog owners", "inconsiderate joggers" comments that seem to be prevalent across forums and comments sections everywhere.