Here are some comparison photos of a real hoodie (the De-lovely one) and fake (wannabe Seagrass):

Slightly glossy size tag; clean zipper:

YKK zipper--I would say this is a very good indicator as I would imagine that fakers wouldn't think to purchase them since they're probably more expensive, but someone correct me here if I'm wrong:


Colored size tags should correspond with the hoodie's color and should state the letter size (P/S/M/L/XL) followed by the French (??) numeric size: