What is this lists' plan vs X, Y or Z list?
Replace X, Y & Z with lists that you expect to encounter on at least a semi-regular basis (and obviously, don't limit yourself to just 3).
If there's one or more lists that you know you'll end up playing this against & you can't answer the "how do I deal with it?" question to your own satisfaction, then unless it has amazing matchups vs everything else that would be a good indicator that it's not going to serve you as well as you'd hope.
The first question I ask myself as I build a list is: will these other things help Corran Horn in the current meta?
I'm pretty much addicted to Corran, so whatever pairs well at the time is what I try.
Whoever you are, whereever you are, I will find you and drop direct hit Proton Bombs on your precious E.Wing!
"Does this list have enough Firespray in it?"
unless it's Rebel, in which case
"Does this list have enough ARC 170 in it?"
"Do I need to buy anymore ships to get the cards needed to be able to fly this?"
For different reasons, I'm happy with a yes or no!
For me it's usually:
1. Is this efficient?
2. What are some bad matchups - how likely am I to encounter them?
Does this list have exactly 10 shields?
I own 10 acrylic shield tokens so I get really excited when I stumble across a 10 shield list.
So I actively maintain a list of pilots that are strong and have unique abilities in the current meta. This goes along the lines of, "Can your list deal with Soontir?" Thinking about a list in terms of specific matchups helps me more than an abstracted list critic. Of course they are listed by pilot skill, cause it's super important for listbuilding.
PS2 - K-wing with Conner Nets
PS2 - Lamda Shuttle with Palpatine & Electronic Baffles
PS2 - TLT Y-wing
PS3 - U-boats
PS3 - VCX-100 Ghost
PS4 - PTL Manaroo
PS5 - Countess Ryad with X7 title
PS6 - Crackstim Brobots
PS6 - Asajj Ventress with Shadow Caster title
PS6 - Vessery with Tractor Beam
PS7 - HLC Dash Rendar
PS8 - Omega Leader
PS8 - PTL Inquisitor autothrusters
PS9 - Dengar
PS9 - Whisper
PS9 - PTL Soontir Fel autothrusters
PS10 - VI Corran Horn with R2-D2
"What does the list do when faced with Soontir?"
Sad, but true. He's an extreme end of the spectrum and if I don't know how the list would answer him, there are a handful of Imperial ships who are likely to be real trouble.
This, i pretty much ask this for every list i build for standard 100 point dog fights, i usually add in dengar and x7 defenders now too since stress and wampa were such good answers for soontir.
The add on to the question "is there any one ship in the game that can completely ruin my day"