Hi.
I did particularly poorly the first time I took the GREs both subject and general. I was a bit sick that day. My math score was in the 82nd percentile and I even managed a relatively low score on the logic portion of the general GRE. However, I had high grades in my major and, previous research experience, and (I hope) good letters of recommendation from my professors. I ended up in Rutgers and was very happy there.
My simplest point echoes that of the earlier comment. I imagine that you are admitted to graduate school based upon a variety of factors. The GREs may be important, but not the only important consideration.
I'm not sure that my or another person's anecdotal evidence will be most helpful to you. I hope that we may be able to coax someone who actually sits on a graduate admissions committee to comment on the selection process. I bet that the same way I have issued a disclaimer, such a person would say "admissions differs from university to university" but I believe their input might help you more.
Good luck with your graduate studies. I know it will be tough but I hope that you'll remember to find it enjoyable as well.
Best Wishes,
Dov ;-)