It all started when Seven billed itself as "SE7EN." We can give Seven a pass because it's a good movie and the numeral 7 does actually look a little like a V when placed among a bunch of capital letters. Clever. Great.
Murder by Numb3rs was annoying but at least held to the "numeral that looks like a letter" idea.
It got worse when you start seeing Five written as 5ive, which makes no damn sense since 5 doesn't remotely look like an F, and looks like it should be pronounced Sive or maybe even "fiveive." Just because it's the same number you're writing out doesn't mean you get a pass. I forget who did this, but someone did.
Recently we had the movie Lucky Number Slevin, which sometimes was written as "Lucky Number S7evin." Bad enough that they're cheating on the title pun with the ridiculous name "Slevin," which seems to be reverse-engineered from the title rather than a clever play on an existing name. But to insert the number 7 into it on top of that when the word isn't even really "seven"?
It gets worse:
The original posters had "S7evin." The banner ad from Deep Discount DVD has "Slev7n." The DVD itself gives up on the numeral substitution and instead swaps out "Number" for "#." No. Sorry. You've run out of chances to change the name of your movie. You can't even decide what letter you want to replace with 7, and now you're throwing out whole words?
I'm surprised they never tried "Sle7in," but I guess that would have made the connection to "Se7en" too obvious. Maybe they should have called it Lucky # S7e77n. Or maybe [four-leaf clover] # 777777. Why not? Numbers and symbols are just as good as letters. People will figure out what it means.