I use pretty standard commands, including lots of common English words. My dogs only respond to them when said in a certain tone and/or paired with the dog's name, though. I've never had a problem with confusing my dogs when the words come up in conversation. Even phrases like "go to bed"...if I say, "Hector, go to bed," in a firm tone, he'll go to his bed. If I tell my boyfriend, "I'm falling asleep on the couch so I guess I'll go to bed," he doesn't even flick an ear at me.
The only time I have seen using common words be a problem is when people use them as marker words, and it's because the person tends to overuse them, not because the dog doesn't know the difference between a "Yes!" as a marker and a "Yes, dear," sighed over the phone.