Send any friend a storyPortia Kapraun has always seen unwelcome ads on Twitter, usually from major brands pitching her luxury jewelry or vehicles that she, as a librarian in Indiana, could not afford. Corey Richardson, vice president at the multicultural ad agency Fluent360 in Chicago, said he was seeing more ads for items in which he had no interest — Hawaiian shirts featuring “Star Wars” characters, a fountain shaped like hands folded in the prayer position, all mixed in with vaccine misinformation and the occasional video depicting violence. Their ads are designed to evade “very brittle” moderation algorithms by spacing out the letters of banned keywords or replacing them with emojis, he said