An allusion can preserve a literal meaning while suggesting a further intention. If the association is familiar, the listener can infer the intended sense; when it is excessively remote, semantic complexity may result.
Clear allusion: «فلان كثير الرماد» — abundant ashes may suggest frequent cooking and thus hospitality.
Unsuitable allusion: referring to spies as «ألسنة» (“tongues”) — the intended connection is not sufficiently evident.
Figurative expression is not the defect in itself. The relevant test is how intelligibly and appropriately it communicates the intention.