Often, hilarity ensues. The beautiful dress on the website with layers of lace and beading arrives three sizes too small and, instead of the beading and lace in the photo, it will be cheap, stretchy fabric printed with vaguely lace-like patterns and a few badly-glued sequins scattered around.
I've had my share of successes and failures on these sites.
Last month, I tore a hole in a pair of gym tights.
Instead of paying $100 for a pair from a sports shop, I took a punt and bought a pair online for only $7.
Well worth the risk, especially with free shipping. Or so I thought.
Reader, it was not worth it. I couldn't pull them past my ankles. And even if I could have got them up my legs, the fabric was only a touch more opaque than pantyhose.
Compare that experience with one recently when I saw some gorgeous tassel necklaces at a local market and shuddered at the price.
I did a quick search and found identical necklaces for less than $10.
I bought three, they arrived this week and look fantastic.
Sometimes these sites are worth the gamble. But if you're not a gambling person, it pays to remember the old adage about getting what you pay for.
After all, the only people who will benefit from buying bad knockoffs are YouTubers.