In the literature about what sorts of things have a truth-value, the idea that acts of belief bear truth-value seems present, yet uncommon. On the other hand, objects of belief like propositions or sentence-tokens seem more popular as candidates of being the bearers of truth-value.
However, when the main topic at hand isn't what the bearers of truth-value are, I see beliefs be described as true or false all the time. For example, the vast majority of epistemologists regard knowledge has being some kind of true belief. Also, a justified belief in a non-deontological sense normally just means the belief is sufficiently likely to be true.
According to the SEP:
Sufficient Likelihood Justification (SLJ)
S is justified in believing that p if and only if S believes that p in a way that makes it sufficiently likely that her belief is true.
This suggests that most accounts of justification require a belief to have a truth-value.
Personally, I don't see how a belief can be true or false, but that's not the main point of the question, although if someone could provide an argument for it, I'd be interested.
What I don't understand and want to know is why it seems to me that most philosophers don't take beliefs to bear truth-value in the literature specific to the topic, yet on other topics seem to presuppose that they do? Perhaps I'm missing something.