No, 100% het means they are definitely carrying the gene. You just can't see it. But just carrying the gene isn't enough for every baby to be a clown. Passing the gene is still going to be 50% chance. Unless you breed 2 clowns together, you will never get all clown babies. Breeding your het to a clown means each egg has a 50% chance of being a clown.
Here's a couple image example:
Just replace albino with clown. Same genetic idea. You need aa to carry to the baby for it to be 'clown'. The rest would be hets or the AA would be 'normal' with no genes.
The 50% or 66% hets are badly named in my opinion. They should ALWAYS be labeled as 'possible het' because those are the ones that may actually not be carrying the gene. Those are for gamblers or very lucky people. That is the het to het breedings.
There's also http://www.worldofballpythons.com/wizard
Which if you plug in the male and female of what you want it will give you a fairly accurate % of what you'll get.