Truth is there are countless stereo-types given to each gender. My opinion is simple: all Cavalier King Charles Spaniels are smart and can be taught right from wrong. Potty training and marking are two very different training issues. Both genders are capable of marking. Males tend to mark if they come into contact with a female in season once they are old enough to sire a litter which is around 18 months of age. Females mark for odd reasons and can be more difficult to correct. A female might mark when being left alone or something. To get around this issue it is best to always crate train when you are gone so you will know your Cavalier King Charles Spaniel (dog) is safe from developing a bad habit of marking.
There is a saying amongst Cavalier King Charles Spaniel breeders and it goes like this: "Females love you, but males are in love with you." Every Cavalier King Charles Spaniel is different as to how it goes about showing its affection for its owner. I have had some males and females that are born snugglers and I have others that are more sporty and would love for you to throw their toy so they can retrieve it. As Cavalier King Charles Spaniels mature in age I have found the males stay a bit more outgoing towards other people and activities outside the home, while females tend to get a bit more home-bound and tend to create a comfort zone of showing their affection only to their family members.
If a male Cavalier King Charles Spaniel is neutered around 12 months of age and fully housebroken I can assure you he will remain housebroken. My husband has to keep the reins in check with me as each litter comes along because placing the males is always harder for me because they do show so much more affection than the females early on in a litter. Females are the alpha gender in the canine world, so females routinely strive for the top pecking order early on and continue to show their dominance until they are placed. Males know they are not top dog and come to me much quicker wanting to be held. I recommend to anyone looking to adopt a Cavalier King Charles Spaniel to focus on temperament and not to let gender be your main priority because you might miss out on a remarkable relationship if the other gender had a temperament that met your lifestyle better.