Whatever is given unwillingly, keeping in mind some return benefit from the receiver, or expecting some personal gain, is held as rājasa dāna.
If sāttvika gift is pure, desire-free and without expectation, rājasa gift is just the opposite. It has the definite aim of getting some reciprocal benefit from the beneficiary. But any such thought is desecrating. Rajo-guna drags the giver to such retrograde instigations.
The rājasa giver being possessive, will be very reluctant to spare what he has. He will not give spontaneously out of compassion. Only when love and fondness adorn the giver as well as the receiver, the offering becomes noble, elevating and delightful.
Dāna often promises heavenly rewards, which motivate the rājasa giver. But any such thought undermines the whole nobility and sanctity of dāna. True discrimination alone is the real safeguard in the matter.