My knowledge of sexing albigs has grown from learning, experience (13 years with monitors alone), and making mistakes in the past. You are free to check the archieves here and verify that the only one who was sure on Sobeks (BT/WT/WT cross) sex as a female before I found out by her cycling (and it was only a few months before) was FR. Of course a few people said afterwards that they new she was female. Guess what, I learned the hard way on that case also because Sobek has always had bulges under her tail base (almost as big as my friends male Sienna Leguaan), but they are not BULGES like my male BT/WT cross. There are a few points that give it away, the head shape, the body shape (also around the base of the belly before the hips), the nose shape, and of course what everts. When a male albig everts even at 18 inches long it can not be missed it is big, and they do it often. I have pics of a manual eversion of my male as its not easy to get pics of naturally. The female everts a thinner shorter hemiclitori that appears on the end like a roll, where as a males hemipene has a large "flowered" end and 2 finger looking projections. One important point female Albigs scent mark as much if not more than some males do (Ive had a few of both), as a matter of fact Sobek for example scent marks to cover up from my male (Shadow) in the yard as well to cover up when cats, dogs, and other animals scent mark there. She rubs her vent, her back legs, her hips, her tail, her stomach, her front legs, her chin, and lower jaw against the ground.
You know what, both of my albigs came from a long time world famous breeder of albigs, niles, argus, and other species that thought for Shadows first 2 years of life he was a female, I could tell after he showed up he was male, and even by looking at the picture that was on the website he was for sale on. Rob was very suprised that Shadow was male, Im suprised no one else caught that by seeing the picture on the website for so long. heres the pic from Robs old site before I bought Shadow (in this pic hes 2 years old). The link is of myself popping Shadow, posted on a friends website.

Picture of Shadow during manual eversion (popping).