Some actors can shoot themselves in the foot before they even read for the part. They come in and talk way too much. Or the kiss of death is to talk about how great the real product is, like, “oh Man I really do drink Budweiser.”
Some of it comes down to the fact that the agency and the director are all going to be hanging out with you for 12 hours a day when your shooting and if there are 2 people and one of them is friendly and nice and the one of them is annoying - and they both can do the job-then definitely the friendly nice one is going to get the job. Because it comes down to "who do I want to spend my day with?"
So personality does come into play. You don’t want to overstep your bounds, you don't know these people that well, and they are not your friends in that moment. Remember you're in the audition room to do a good job. That doesn't mean you can't be personal and get a laugh out of them or something but read the room and act accordingly. Keep it professional.
Ross Lacy is a Casting Director who, over the course of almost 20 years, has worked with every major advertising agency & production company worldwide. He's been responsible for casting seminal spots and launching unforgettable campaigns. He has cast over 3,000 commercials, many of which have won Clios, Cannes Lions, and have been featured in the pages and on the cover of Adweek.