In GMC Advanced Chapter
Although most consumers are suspicious of such offers, Colin wants to purchase the two-for-one vacation package.
Consumers suspect such offers is unidiomatic.
But the sentence
Many directors have a suspicion of there being an attempt by managers to conceal the extent of losses at the company.
Can be modified to
Many directors suspect that managers are trying to conceal the extent of losses at the company.
Could any one please explain when should I consider changing "suspicion of "or "suspicious of "to "suspect" ?