Possible Clues:

• Caution: The fog gets it rusty
• Have no confidence in (someone)
• Suspect 'spray' precedes 'decay'
• Suspicion of corrosion after condensation
• Be suspicious of The Cloud - it's corrosive
• Be suspicious of vapour with reddish-brown colour
• Suspect signs of damp and decay?
• Be suspicious of some nonconformist rusticated
• No confidence water vapour leads to corrosion
• Suspicion of haze, result of dampness