Funniest Ad Copy For Counterfeit Stamps, Ever

[bold added by me]

Uh . . . does this seller actually sell "stamps" with the slash mark still on them? No one is that dumb that they would buy them, right? Or is it just the images he's showing that have the slash mark on them? You better order some and find out!!

Danger. One of the rolls of flag stamps is upside down. According to the U.S. Flag Code, this is to "signal distress." The customer will be distressed when realizing they gave a credit card number to a counterfeiter.

In regards to the original poster's message: thank you for sharing this bizarre note.

Actually it makes perfect sense to me. The USPS has done this type of marking in their ads, catalogues etc. on and off for years, depending on the size of the images printed. The wording is awkward, but the seller is actually trying to be in compliance for imaging US postage.
There has been a secondary discount market for postage for decades, since 1847 in the US probably. My partners and I moved millions in discount postage over the last 40+ years. We put a variety of stamps on envelopes for local companies making up the current 1 ounce rate and charged them 80% of face. Of course that part of the business has dwindled significantly in last decades with the drop of stamped snail mail use by businesses. We also sold mint stamps in singles, plate blocks, sheets, coil rolls etc. to anyone interested. Perfectly legal as long as stamps not "skips" or certain use such as postage due, official etc. We even sold to the local USPS Lower denominations during rate changes.