I'd lean towards only using faction standings as a tool to gauge initial impressions.
If someone says they're an X faction loyalist, and they have terrible faction standings with X faction, then it feels a bit odd to me.
If they never do anything to improve those standings, or they get worse, then it feels even odder.
for pirate faction loyalists, it feels odd if they do this. Like, I've seen some self-proclaimed "sani sabik" actively running missions for e.g. Amarr Navy. It doesn't make sense to me. If they had terrible blood raider standings but were actively missioning for blood raiders, then it would make sense, even though their standings are poor, because they're doing something to improve them.
That's why i like Valerie's corp, since they seem to only have standing with the Blood Raiders.