Were these APA shows? I know that the APA is super strict on this sort of thing, and it happens more at 4-H and state fair type shows. I've been to a good number of large APA shows, and have VERY seldom seen an ill bird (at least from outward appearance).
I do take Oxine solution with me, and spray the cage & shavings thoroughly before putting my bird in; I also spray the bird directly, as well as the cage, several times throughout the show. I have sometimes gotten odd looks from folks when I do this, but it's a precaution that is mandatory to me, so I just smile & go on with my work!
One was APA and others were smaller but I couldn't believe how sick they all were. All the bantams were shaking their heads with snot. Some of the turkeys had pox and almost all had at least 1 eye swollen. It makes me nervous about showing...if I ever get there. lol I'll keep some Oxine solution on hand though. Does Nolvassan solution work as well?