I love the online marketing I see for apartments.  Consider this ad from the first page of Boston apartment listings on Craigslist (at the time I happened to look, of course):

We haven’t seen lower prices at this luxury high-rise. Call today!
1 month free
$1,890 / month

…

Effective rent only $1911 per month after free rent special on 12 month lease.

If the regular rent is $1,890 and there’s one month free, that’s effectively $1,735, not $1,911.  That’s a difference of $176.  I feel like there’s a great chance one’s hypothetical security deposit would get lost in that mathematical shuffle pretty quickly.