Is this a alternative medicine fad? "stool that sticks to toilet bowl can be a sign of malabsorption, disease, etc?"

Yes, a fad: Occasionally alternative medicine does a good job but one needs to pick the good from the nonsensical. There is no study to support its claim on the character of stool. In fat malabsorption, the stool tends to be loose and soft and even greasy.

This is not a sign!: Stool sticking to toilet bowl is not a sign of malabsorption. Watery stool is more often an indication of malabsortion of carbohydrates; excess gas often accompanies. In fat malabsorption the stool becomes more "oily".