This is one of the most common misunderstandings when it comes to genetics. When you cross a rabbit that has one copy of a gene (in this case, the gene for the Rex coat) to a rabbit that has two copies of the same gene, each of the babies has a 100% chance of getting that gene from the parent with two copies, and a 50/50 chance of getting it from the parent with only one copy. That is not the same thing as saying that half of the babies will have the Rex coat, and half normal coats. It's like flipping a coin - if you flip 6 coins at the same time, you could get 3 "heads" and 3 "tails," but you might just as easily get 2 and 4, or 1 and 5, or even 6 heads or 6 tails, and all of these results would be perfectly normal, given that you only flipped that many. The same is true when it comes to litters - because the sample size is so small, you could get results that are far from an even split (even all Rex or all normal coats) and it's perfectly normal. If you could do the same cross enough times to get 1000 babies, you would probably get numbers that were close to 500 of each coat type, but in a sample as small as 1 litter, or even the entire lifetime production of a breeding pair, your results could be widely skewed.
But - and this is important - there is more to the Rex coat than just short hairs; there are things like density and texture. These are determined by other genes, which may or may not get passed on when the Rex gene gets inherited. With crossbreds, you might get short coats, but they might be fine-textured and thin and nothing like the thick, plushy, springy coat that one expects to feel when they handle a Rex rabbit.
When crossing to a (I'm assuming Holland Lop; "Lop" isn't a breed, just a description of what the ears do) you have a different issue. The ears on the Lop breeds go down because the rabbits' skulls are wide and because the ligaments at the bases of the ears aren't strong enough to hold them up. Outcrosses, particularly with something as small as the Holland, often wind up with what I call "Weeble ears" ("they wobble but they don't go down"). You can't very well call a rabbit with mostly upright ears like that a Lop; it's a small mixed breed. Now, whether you could sell that depends on the market in your area; around here, there are enough purebreds available you'd almost have to give them away.
I don't know about you, but I consider missing most of the nerves that go to the muscles lining the digestive tract and megacolon to be a bit more than minor issues. Every Charlie is born like that; some die very young because their digestive systems are so dysfunctional while others live for years, but all are just about guaranteed to experience GI stasis episodes, no matter how careful their owners are.
They stick out sideways but they don't fall correctly, like airplane wings. Very cute imo but some people find it unattractive.
So while some people may be of the opinion that the condition doesn't exist, or if it does, it is rare, in certain circles it's been accepted for years that Charlies are born with the structural deformities that are associated with megacolon, whether or not they show symptoms.
My personal experience with Charlies is very limited; I avoid breeding them, and have only owned 3 or 4. With such a small sample group, I would be hesitant to put forth my observations as having any real weight, but I will say that they have borne out what I have heard for years; they all had the weird poop, and tended to develop GI stasis at the drop of a hat.
