Disguise them! I actually did this with Emilu (enter a specialty show - not disguise her!) It was put on by a poodle club of all things, but I didn't realize that the Rally show was just for poodles too. I entered through Infodog, and they sent it on to the trial secretary, who notified me and said that I couldn't enter. I think I entered 2 shows, and paid an extra fee because of the secretary (don't enter through infodog anymore). I notified infodog, and eventually got my money refunded (it was before the entries closed). So no - although I don't know if a specialty club could put on a show and have it not be just for their breed - I mean, I guess they could, but I don't know if they do. If there is anykind of specialty involved that day, then the obedience is proably just for that breed too. Come to think of it - the premium did say that it was just for poodles, but I hadn't seen the premium and didn't notice it when I made my entry.
Linda I have found the AKC website very helpful in determining if a specialty has all-breed obedience or not. Some specialties close it to that breed only and some don't. Example Miami Valley Lab Specialty had all-breed obedience but Winnebago Specialty did not--Labs only. So as has all ready been said, it is up to the club to make the determination.
It is entirely up to the club. For example, the Lab club here used to be Labs only but they recently opened it up to all breeds so they could get more entries. I'm thinking the Golden Club probably wouldn't need more entries.
Sometimes it also depends on what is going on around them. For example, if an all breed show is scheduled the same weekend within 200 miles (I think it's 200 anyway), then the specialty couldn't offer all breeds and the all breed couldn't accept entries of the specialty breed. Yes that's right...you are forced to attend the specialty if you own that breed.
We had this happen last year. Several clubs moved their show dates. An all breed club moved their show date right over the top of the GSD specialty which had all breed obedience so AKC told the all breed club they couldn't offer obedience no Sat/Sun because they were within 200 miles of the GSD show which was in Tucson. The all breed club figured out a way around it. They added a double trial on Fri so anyone wanting to show in obedience could have attended the double trial Fri at the all breed and still gone Sat/Sun to the GSD show.