What to do when it comes to 0s and negative numbers as roll results

So, earlier today, I was looking over an interest check a friend of mine had made for his Aztec-Fantasy hack of AW on a RPing site we frequent, and noticed that when he listed the result possibilities for every roll made, that he listed the 1-6 result as 2-6. I pointed it out to him, and he said it was supposed to be 2-6, but I pushed on with the knowledge that it was supposed to be 1-6. So, finally, he said that then it would allow for 0s and negative numbers as roll results (something I've never seen in any game I've been in, but still feasibly possible) since one stat has at least -1, there can be debilities that further reduce a stat by -1, and Aid or Interfere allowed for players to add another -1 to said roll. After that, we then got onto the discussion of what to do in the event of a player rolling a 0 or a negative number. He said that he preferred that it counted as a player had gotten a +10 or +12, as a result of failing so bad it worked, while I was more in favor of allowing for players to reroll for said move.
So, what I want to know is, what do you more veteran GMs do in this situation, if it feasibly happens?
-Zed
P.S., Lumpley, if you could give your input on this, it'd be great, seeing as how you're the progenitor of the system.

In AW a 6 or less is a Miss, right? So a negative number is still a miss.

In an AW hack, that would be up to the designer.

Well... the possible results of a character in AW is -4 to +18. You can have a character that starts with a stat of -2, has a disability, a -1 forward, and someone interfering with their roll to hit adding another -2. Likewise, you can have someone with a stat of +3, being aided +1 with a +2 forward from battle babe's read a sitch bonus.

A non advanced move hits the same on a 10 as it would on a 17. In the same way a character's miss is a miss no matter how roll they low. Hitting them harder doesn't seem fair. Nor does it make any sense at all that someone interfering with someone who already stands little chance (thus giving them a bigger negative) would somehow accidentally aid them. That's just silly talk.

Don't write it as 0-6. That is incorrect. You have 10+, 7–9, and 6 or less. Hit, Partial Hit, Miss; respectively. I would be very wary of home-brewing any hack or rule that would suddenly make it beneficial to roll stupid low. You'll just be making things far to complicated. A miss doesn't mean a failure anyway, it just means there is a hard move happening that may or may not make what they were attempting to do less valuable. You can tell them they succeeded in getting across, but the reasons they were trying to get across in that sitch change while they're doing so. Like running for the exit they thought was freedom... only to get to the door and find 20 guys aiming guns at you. That's a miss, but it didnt mean the boys shooting at you stopped you from getting to the door.

Well... the possible results of a character in AW is -4 to +18. You can have a character that starts with a stat of -2, has a disability, a -1 forward, and someone interfering with their roll to hit adding another -2. Likewise, you can have someone with a stat of +3, being aided +1 with a +2 forward from battle babe's read a sitch bonus.

A non advanced move hits the same on a 10 as it would on a 17. In the same way a character's miss is a miss no matter how roll they low. Hitting them harder doesn't seem fair. Nor does it make any sense at all that someone interfering with someone who already stands little chance (thus giving them a bigger negative) would somehow accidentally aid them. That's just silly talk.

Don't write it as 0-6. That is incorrect. You have 10+, 7–9, and 6 or less. Hit, Partial Hit, Miss; respectively. I would be very wary of home-brewing any hack or rule that would suddenly make it beneficial to roll stupid low. You'll just be making things far to complicated. A miss doesn't mean a failure anyway, it just means there is a hard move happening that may or may not make what they were attempting to do less valuable. You can tell them they succeeded in getting across, but the reasons they were trying to get across in that sitch change while they're doing so. Like running for the exit they thought was freedom... only to get to the door and find 20 guys aiming guns at you. That's a miss, but it didnt mean the boys shooting at you stopped you from getting to the door.

Alright, that's reasonable, and besides, the only reason my friend and I brought it up was because of his typing error.
Anyway, thanks for the input, everyone.
-Zed