Bs6+ negative modifiers

So what does one do with modifiers when modifiers make it so that you can't hit on a 6+. Say with a -1 to hit. So needing 7s to hit. Does a 6 still always hit? I know 1s are always a fail.

Any page reference numbers?

Thanks

If you are referring to overwatch, 6's always hits.

Not referring to Overwatch.

Imagining orks being BS5+, moving with a heavy weapon for a -1 and shooting at a flyer for another -1.

There is nothing in the rule book about a 6 always hitting (other than in overwatch). So technically it's possible to make it so your unit is impossible to hit. I had to play against this yesterday with a few people playing Tau and loading up on Ghostkeels and Stealth drones.

Its very possible to make some units impossible to hit.

Keep in mind that the FAQ ruled that a dice roll can be modified above a 6+. Albeit, the examples list saving throws, however, if you can have a 7+ save, I don't see why you can't have a 7+ to Hit.

You can have a 7+ to hit just like save. Unfortunately that means that any roll of a D6 will never achieve the score required.
Unless you can get some other ability in there to boost it again.