This raises several questions, however. For instance, is it acceptable that a person only deceives another if he is weak or malicious? or, can a person not deceive another person even if he is more powerful, and/or even if she is not being malicious? Cannot it not be that there exists a more powerful, and non-malicious, deceiver?

So basically, for Descartes, God is an entity that cannot lack in anything; and as deceiving means to lack certain positive qualities, he cannot possibly be a deceiver as he does not lack.

This viewpoint dovetails nicely with Plato's republic and the Cave allegory in that it presents a very black-and-white depiction of God and God's abilities, virtues and perfection.

That is why Descartes is unique: He paints for us a simple view of God in some ways.

The Counter-Point

One may argue against Descartes on the idea that evil may well be a quality in itself, as opposed to simply the lack of the quality of goodness.

Basically, the argument here is that negative space - in its lack of foundation and being - actually constitutes space. Perhaps evil is actually a quality, and since God has every quality - not just those we ignorantly assume are positive - he is evil...

This belief still requires that we as humans agree that deception is evil. And as established above, this view may be hotly contested. Indeed, perhaps some forms of deception - a surprise birthday party, for instance -- are not evil.
In Descartes Medications, as the notion of the will to deceive linked to "weakness" waxes vague, it is possible to consider the claim that the will to deceive is linked to maliciousness. There are two possible counter-arguments here: (1) a person may have the will to deceive another without being malicious; and (2) a person may have the will to deceive another while being benevolent.

But at its most basic form, the arguments against Descartes' views are founded in precisely what makes them strong: the black-and-white nature of his depiction of God, God's abilities and qualities.