Thanks Gals.
I forgot to mention about cheering, clapping, whistling at ringside. It is usual practice not to clap when the dogs are being judged, especially for the puppy classes, until the winner 1st 2nd runner up etc is selected.
Winners Dog/Bitch competition you might clap as all the dogs enter, especially at a National Specialty where lots of folks are pretty pumped, but again we often wait until the end of the judges selections.
BOB competition, clapping usually happens as the Champions enter the ring and do their first go around. Here and most especially at Nationals, people will cheer or clap when their favourite comes up to be judged. Now remember these are champions older dogs presumably used to the show ring. It is kind of like rooting for your team
Some Judges will encourage the clapping as the specials enter the ring. It is a sign of respect to the dogs owners and handlers that they have earned the title Champion.
At a large show with great energy going on Group judging can be a blast. Remember each breed within that group is being represented and many of the breeders that competed that day but did not win the breed, will come out and support "their" breed in group. Catcalls whistles, cheering, clapping when their breed comes up is kind of fair game
How-ever booing is not encouraged
And BIS has the most clapping going on, for each Group winner that individually enters the ring, during the go-around et all.