The case
The sneaker brand that took over the mall in the late '90s has one of the most-misspelled names in retail. The T that people insert comes from "sketch," the ordinary word the name is playing on.
Skechers dropped it on purpose, the same way brands drop letters to make a name ownable. The shoebox, the storefront and the tag have never had a T.
Why our brains do this
Brand names that riff on real words inherit the real word's spelling in memory.
Sources: Wikipedia — Skechers · Wikipedia — False memory: the Mandela effect