Tough Assignment

I have been given the most difficult assignment I've had in school (college), to date.  I've been given two papers, written by two different classmates, which I have to review.  I have to make corrections where I see fit, and I also have to say something positive about them.  Basically, I have to play teacher.

The difficulty lies in the fact that they are both very badly written papers.  I don't have much that's nice...OK, I don't have really anything nice to say about either of them.  I don't want to be cruel or anything, but...

I'll show you a sample—the first two lines of an editorial (opinion piece):
"What do most say when students are getting dunk faster?  Many are thinking this will never happen to me."

What??

I figured that "dunk" was probably a typo, but for a second I did wonder if maybe it was some new slang for some new thing that I didn't know about. But she meant "drunk," which is what I assumed.  So, I'll try  not be that critical—even though this is her third draft.  The real question is this:  what do most of what —students? teachers? people, in general?—say ...  and did she mean about students getting drunk faster?  Or does she really mean "what do they say when students are getting drunk faster"?  And, faster than what?  
But perhaps I am too fastidious.

Fortunately for me, the other paper is a little more lucid.

So I can mark these papers up in any way I want.  I can correct grammar, and punctuation, and spelling, and point out sentence fragments (galore!).  I can suggest the restructuring of sentences, and the rearranging of those sentences within paragraphs. There are so many errors in them that I could do this all night, until these are my papers instead of theirs.   So where do I draw the line between it being their work or mine?  And how do I make all these suggestions without looking harsh and super-critical?

Ugh! Difficult assignment!