I'd suggest you take a look at Gadamer's "Truth and Method".
Despite my better judgment, I'm going to try to flesh out this answer a bit.
First: as the original question points out, the "Socrates problem" is not really relevant to the actual question at hand. The "Socrates problem", in the sense of "the problem of the historical Socrates" is quite unusual in that we possess no texts attributed to Socrates, but rather, three distinct reports of him (coming from Plato, Aristophanes, and Xenophon), each of whom had their own polemical purposes. This problem does not apply to the vast majority of philosophers we're interested in, who left texts.
So, the question then becomes one of the interpretation of texts: how do we know when we have interpreted a text "correctly"? Further, what would "correctly" mean in this case: the recovery of authorial intent? The branch of philosophy [*] that these questions belong to is termed 'hermeneutics', and there exists a vast literature on the subject. If one were interested in a historical view, Schleiermacher would be the place to start, but I wouldn't recommend that, for the following reason:
There exists a seminal text in hermeneutics, which stands as the sine qua non for all later work in the field: Truth and Method, by Hans-Georg Gadamer. Attempting to discuss hermeneutics without reference to Gadamer would be like trying to discuss physics without recourse to Newton-- you'd spend half of your time reinventing his vocabulary, even if you wanted to disagree with him.
In short, if questions of interpretation interest you at all, there's not much point in going any further before you have grappled with this text.
Fortunately, it is available in English translation, ubiquitous at libraries, cheap in paperback, and easy to read.
Thus, in my opinion, there is only one answer to your question: take a look at Gadamer's "Truth and Method". When there is a major philosophical text that deals directly with the fundamental problematic underlying your question, there's no other responsible answer than a simple referral to the text in question. And, naturally, if for some reason one is unable to take the time to read the primary text, there are easily available secondary and tertiary resources which are easily found with the knowledge of the author and title of the primary work.
[*] and/or philology, but that's a discussion for another day.