Quote:
It depends on the quality of your Polish. If it is from a hatchery, some chances are that its crest is small, and only holds one allele , which allows for the chances of having offspring with another bird to have NO crest. If your Polish is of good quality, then yes, crossbreeding it to create F1 gen offspring will give 100% crested birds, but with small crests as shown in that pic.
I've bred 4 different Polish from hatcheries to an EE before - Of those 4, 3 had 100% crested babies, and 1, who had a naturally smaller crest but still claimed "purebred and showable" by the hatchery, had 0% crested babies.