Quote:
Hmmm.. he didn't have his in quotes..
And without a comma, "they're" references the word preceding it.


Disclaimer: I am not taking this seriously at all -- just a fun exercise ;-)

Context is everything:

[In discussing the optical drives in Apple computers] Unless you go with the tower they're POS laptop drives.

In this case, "they're" must refer to something other than "tower" because a) disagreement in number, and b) a tower is obviously not a drive. Given the context, the reference is obviously to the hard drives ...


Similarly:

I love these sandals. Unless you have big feet they're quite comfortable footwear.

and

I love these sandals. Unless you have big feet, they're quite comfortable footwear.

To me say exactly the same thing. The second may be more correct grammatically (and less clunky to read), but adding the comma doesn't really appear to change the actual meaning in this case =)