Paying off a collection account is a good idea. But paying off a collection account won't automatically make your credit score improve.
Not all collection agencies remove the negative remarks from your credit rating after you pay them off.
Before paying off a collection agency for a debt owed contact the collection agency and ask them if they'll remove the negative remarks from your credit rating once you pay them off.
If they don't want to remove the negative remark then it's best to not pay them since it won't help your credit rating and they only bought your debt for way less than what you owed the original creditor.
Only pay a collection agency if they will remove the negative remarks.
Although any negative remarks do eventually get removed from your credit rating after 7 years and no longer impact your credit score.