How reliable are pensieve memories?

[Eddie]

No: HPFGUIDX 157938

Since pensieve memories are _somebody's_ memories, is it safe to
assume the memories are how the donor remembered the event?  We have
never seen  the same pensieve scene from more than one perspective,
have we?

In OotP, "Snape's Worst Memory" may only be how _Snape_ remembered the
event, not necessarily how it actually occurred.  In that particular
scene, we hear James, Sirius, Remus, and Peter talking about the
O.W.L. they just took, including reference to Remus being a werewolf.
 Would Snape have actually been able to hear that conversation and
have it captured in his memory?  Or is these details that Snape has
"added" after the fact based on information gathered later?

Eddie