I don't think it is a spoiler. My opinion is that a sleuth of any persuasion, tough, smart, and/or charming, needs Research.
Research is one of the few skills that works in EVERY case. Also, it does not matter what equipment you are using. It always works. That is powerful indeed.
Here is how I employ Research:
Every time I get a list of suspects, I use Research. If Research pings a suspect, I know 3 things:
1) That suspect has a fake alibi
2) None of the physical evidence matches that suspect
3) That suspect is not guilty because of the #2.
If Research does not ping a suspect, then I will question suspects to add to my list.
This is important: Use Research each time you add to your suspect list until a suspect is pinged. Then you won't unnecessarily ask that suspect for an alibi.
Another thing about Research is if you know you are 1 suspect shy of the maximum number of suspects for a given case and no suspect is pinged, then you know the last unknown suspect is not guilty. It is up to you whether to try and add to the suspect list or not.
For those of you who do not know this, each piece of physical evidence must match one, and only one, suspect. You cannot have a guilty suspect without exactly one piece of physical evidence matching that suspect. Of course you may not be able to match a piece of evidence, but that is beyond the scope of this discussion.
I hope this helps!