What exactly means Good/Bad reads? What is the definition for a good or a bad read?
This is basically a field in the SRF file set by whatever program that created it. Srf_info is telling you how many are classified as good/bad.
As to the meaning of it, typically the tools that generate SRF classify a reading as bad if it has very low quality or fails the Illumina purity filter. Some of this data may still infact align, hence some centres choose to keep all their filtered reads still.