Neutral:
* Her suspiciousness towards strangers made it difficult for her to make new friends.
* The detective's suspiciousness led him to uncover the truth behind the crime.
* The suspiciousness surrounding the company's financial dealings was enough to make investors hesitant.
Negative:
* His suspiciousness of everyone around him made him seem paranoid.
* The suspiciousness between the two neighbors escalated into a full-blown feud.
* The suspiciousness surrounding the politician's campaign was a sign of possible corruption.
Positive:
* A healthy amount of suspiciousness is important when dealing with online scams.
* The suspiciousness of the security guard prevented a potential robbery.
* The suspiciousness of the child's behavior alerted the teacher to a possible issue at home.
The tone of the sentence will depend on the context and the specific situation you are describing.