Searching for "futher" or "furthur" (easy typos) never gives "further" as a suggestion. On enwiki, I get "Did you mean: future" and some matches for pages with misspellings, even though there's a disambiguation page for "Further".
On Wiktionary, searching for "futher" I get "Showing results for fucker. Search instead for futher." and the search results include fucker, fuckers, mother-fucker, and more along similar lines. Surely "further" is a more likely match?