I always look at the key attributes when signing players. But scouting can be a time consuming job, so whatever input my scout can give me I'm willing to listen to. I'm also on the classic mode, so I'm trying not to use too many hours scouting each season.
I'm currently playing a three star right winger in my line up. He's total class both for me, and his national side Spain. So yes, don't always put all the weight of your decision on scout reports.
But do you mean that a youngster with a 5 star (blue) report can turn into a world beater if you tutor him the right way? Say I if find a player with 5 blue (CA) and two (yellow) PA stars, should I sign him up ?