As Ireland prepared for Sunday's match at Murrayfield, O'Sullivan was forced to dwell on the last game in Edinburgh when the Irish suffered an embarrassing defeat.
O'Sullivan said: "The scorelines have been horrendous recently so it's something we're well aware of.
"Quite a few of the current squad were involved the last time and it was a pretty harrowing experience for them.
"If you look back at the video, which we have done, our lineout misfired really badly and we didn't get across the gain line, even from any primary possession we got.
"If that happens in any game it's a huge problem. You've got to secure primary possession and get over the gain line. Scotland successfully denied us those basic principles of our performance.
"So it's certainly an issue that Irish teams have gone to Murrayfield and consistently under-performed. We're pretty adamant it's not going to happen to us.
"The focal point for Sunday is that we need to perform, in the physicality stakes and the mental toughness stakes. Tha''s where Scotland will take us on and if we don't front up in those areas it won't be a game of rugby, just as it wasn't the last time.
"Every Irish coach has gone there with high hopes, so here's hoping it's this time."