Crazed pottery is often considered a sign of age and although it may be to a certain extent, it is mostly due to process error.  This random cracking of the glaze is mostly the result of the product being cooled too quickly.  It is very common to late 19th and early 20th century ceramics, especially to early U.S. semi-porcelain.  Semi-porcelain is a U.S. innovation, but it took a few years to prefect.  Crackle finish is created as an effect and is not crazing.  It is common to many  modern oriental pieces that can be readily found in discount stores.

Both crazing and crackle finish appear on true antique and desired pottery, but appear on modern pieces as well.    Checking and dating marks, if present, will help tell the new from the old.  If none are present, reliance must be on experience and an ability to judge quality.