When Wylla was younger, she loved getting a generous bath from Bean. As she's grown, she's become less tolerant, and will only allow Charlene to give her a few licks.
She's a big girl after all - she can groom herself!
The girls get along 99.9% of the time, but when Wylla reaches her lick limit, things can turn into a small brawl - ears flatten, paws are raised, growls are growled. Once Wylla remembers Charlene is three times her weight, the situation quickly diffuses.
Don't worry, it never gets so heated that someone gets hurt. And once it's all over, they both act embarrassed that it ever happened.