Damning with faint praise

Damning with faint praise is a logical fallacy when someone is attacked through praise of an achievement that isn't praiseworthy or isn't significantly praiseworthy, suggesting that no achievements of theirs worthy of praise exist.

The fallacy is an ad hominem genetic fallacy and is an informal fallacy.

Examples

 * "[William] Paley was not a particularly original writer. For example, his famous analogy of the watch at the beginning of the work was not his invention. And he probably took too much for granted. But he showed very considerable skill and ability in his arrangement of his matter and in the development of his argument. And it is, in my opinion, an exaggeration to suggest, as is sometimes done, that his line of thought is worthless."
 * "Mr Cauz characterised Wikipedia as containing "plenty of cracks on it in terms of the quality". "It's very uneven, the facts are not always correct, the model contains a lot of pitfalls." Damning his competitor with faint praise, he said a big problem was that many users considered Wikipedia to be 'fine' or 'good enough'."

Literature
Damn with faint praise, assent with civil leer,

And without sneering, teach the rest to sneer;

Willing to wound, and yet afraid to strike,

Just hint a fault, and hesitate dislike.

When needs he must, yet faintly then he praises,

Somewhat the deed, much more the means he raises:

So marreth what he makes, and praising most, dispraises.

Not always a fallacy
One important note: Damning with faint praise is only a fallacy if it's being used to talk about the position advanced by someone; it is not a fallacy if the subject being discussed is only the person in question.