We run into this a fair bit of the time with Hyperscan. One particularly noxious anti-pattern that can arise is the "prefilter that isn't" anti-pattern: specifi

We run into this a fair bit of the time with Hyperscan. One particularly noxious anti-pattern that can arise is the "prefilter that isn't" anti-pattern: specifically, a multiple stage pipeline where the initial stage is meant to filter out some portion of false positives when feeding to a more expensive check, but isn't doing its job. The painful thing is that the expensive check downstream winds up doing everything, but the code still "works" because the expensive check is the only necessary part (well, as long as the pre-filter isn't totally hosed and isn't producing false negatives).