I agree with the sexes in the pics ... perhaps I should amend ... they can be hard depending on race and size. The common color phase is easy enough to sex unless really small before the differances in headshape, fins or color appears. Plus at the store they are usually washed out. Once settled in at home and have some size on them, not a problem.
Those turquoise color strain is harder though, the females don't get the red and the male's head profile isn't the same as the common guttatus, so it's harder as the fins aren't always reliable. Lili's also the head shape isn't as prounced.
Plus not everyone has the same expeirence level with westies as we do bernie! *lol*