few characteristics of bad links are:
- Low authority domain
- Repetitive links on same domain
- Relevance with the content
- Suspicious embedding of link in keyword anchor-text
- Reciprocal exchange
- Disjunct from meaningful content
- Participating in link schemes
Hence, thoroughly analyze your link building strategy and make sure these does not have any of the above mentioned features. Write quality content, post it on relevant sites, build links on high authority domains and win the manual link building race.