An example of marketplace spamming, where multiple copies of the same shirt are being sold. Note how there's a different creator for each one, and not all of them sell for the same amount of Robux.
Marketplace and Library spamming is the act of players or groups creating hundreds, if not thousands of duplicates of items, typically via a bot program into the classic clothing sections of the marketplace and free to take sections of the development library. There are multiple rationales for why this kind of catalog spamming occurs.
Marketplace spamming
Marketplace spamming involves the mass upload and sale of classic clothing (classic shirts, classic pants, and classic t-shirts), often stolen from other creators on the platform. Frequently, the clothes are those of a popular designer or clothing set, though it could also be clothing that has been taken off-sale. Prior to classic clothing upload fees being introduced, players with Roblox Premium could have reuploaded a piece of classic clothing that is on-sale so that they would not need to spend Robux on that item.
Some marketplace spammers believe players won't investigate whether the item is original, either through convenience or no knowledge of who the original designer is. This gives the duplicate clothing creators the opportunity to earn Robux that might have otherwise been spent purchasing the original item. As the original item is rarely identifiable, the duplicate clothing creators are able to set the price of the clothing to be potentially higher than what the original designer is selling it for.
Some catalog spam bots are capable of replacing the classic clothing template to possibly obscure the original creator. The catalog spamming bots can chain off copies, making it harder to identify content. Clothing botters may also set the prices of the botted clothing to 5 Robux (the lowest price possible) to gain more purchases, as users would mostly buy the same piece of clothing which has a cheaper price than the same piece of clothing which has a higher price. Typically, copied items duplicate the names of the original item. There are also bot varieties that add [ORIGINAL] to the front, emojis, or convert the text partially. The description is often full of unrelated tags set by the bot, but they may occasionally be customized to fit the uploader or group, or instead directly copied from the original.
Library spamming
Library spamming is a similar practice within the development library. This can involve mass amounts of free-to-take models, decals, meshes, and sometimes audio being uploaded in mass amounts.
A common use of library spamming for models is to spread models infected with Lua viruses to attack games. Some botters also use this method for development items to promote their social media platforms. A notable user of this tactic is Qervac (also known as h0nda1337 or h0nde). This method is still heavily used today for self-promotion.
Criticism
Marketplace spamming is frequently criticized by both the Roblox classic clothing design community and customers. As more duplicate items of a piece of clothing are created, the original creator has less probability of earning the Robux that players spend purchasing the duplicate items. Many classic clothing designers have created watermarks in more hidden parts of a character, such as the underside of the torso or the top of the legs, that serves as a part of the original design that identifies it as theirs. A major subset of criticism is Roblox's lack of action in fixing these botting issues or clothing theft in general.
Users looking to purchase specific classic clothing items heavily criticize this behavior, because users can't find anything but the same item of classic clothing unless they use another search term, which only shows them one more item of clothing over and over. Users looking to only buy from original creators find it hard to locate the original creator of a piece of clothing since hundreds, if not thousands of copies of the same item have been put up for sale at a similar or higher price with most ties to the original being lost. This has led to original classic clothing designers focusing on trying to encourage sales outside of the marketplace, such as being featured in notable experiences, using or creating clothing stores, or advertising themselves on social media.
Library spamming is also criticized for having minimal safeguards in place to prevent it from occurring, with moderators only stepping in manually when issues arise on the first pages of searches.
Roblox has added upload limits per hour to some asset uploads along with funCAPTCHA checks when uploading multiple items in a short period of time presumably to reduce botting, but some legitimate developers view the limits and repeat verification checks to be an inconvenience while uploading multiple items.