Neither RAID5 nor RAID6 give you integrity checks. Each block of data is only read from /one/ disk, unless that disk is failed (in which case parity & data is read from the remaining disks to calculate that block).
If the disk recognizes the sector as bad (through its own, internal redundancy checks), then (depending on RAID implementation) either that one block will be read from parity or the entire disk will be dropped from the array.
But, if the disk silently corrupts data, RAID5/6 will not protect you. In fact, it makes the problem worse; silent corruption is more likely the more disks you have)
If the disk recognizes the sector as bad (through its own, internal redundancy checks), then (depending on RAID implementation) either that one block will be read from parity or the entire disk will be dropped from the array.
But, if the disk silently corrupts data, RAID5/6 will not protect you. In fact, it makes the problem worse; silent corruption is more likely the more disks you have)