Crocs are a somewhat maligned brand of footwear and the butt of jokes about peoples fashion sense. Crocs are a brand of footwear that were designed as a boating shoe and rapidly become a popular fashion item. They are a one piece molded type of footwear that is easy to get on and off and come in a lot of different colours and styles. They are comfortable, but probably not that good to wear on the feet all day, every day as they can make the feet sweat a lot and the toes do have to flex to help them stay on, which in some people can create problems long term.
There is no doubt about their popularity and there is also no doubt about the jokes and comments they get. They are a source of a lot of memes:
A few have even used Crocs as running shoes and done all right in them, but that is not recommended. However, those that do use them as running shoes do claim that they last much longer than a running shoe and cost a lot less than a good running shoe.
Like most footwear types, there is probably not a lot wrong with Crocs if you use them for what they are intended to be used for and use them in moderation.