Word maps with constants on symmetric groups

We study word maps with constants on symmetric groups. Even though there are mixed identities of bounded length that are valid for all symmetric groups, we show that no such identities hold in a metric sense. Moreover, we prove that word maps with constants and non-trivial content that are short enough have an image of positive diameter only depending on the length of the word. Finally, we also show that every self-map $G\to G$ on a finite non-abelian simple group is actually a word map with constants from $G$.