Who a company hires has a direct correlation to salary.
The companies that pay pilots low wages are more likely to hire based on if you have a pulse.
The companies that pay their pilots high wages seem to be extremely picky.
Honestly there seems to be no no rhyme or reason to who they hire. I've seen the most personable, easy going, smart, pilots who posses amazing flying skills, leadership qualities and integrity not get hired by desirable companies such as SWA or FEDEX.
Then there are guys who somehow slip through the cracks with felony DWI's, violations, failed checkrides, etc who get hired with very desirable companies. Some of these guys are alcoholics, have the personality of a wet mop, can't make a decision to save their life and seem to have never flown an ILS.
I think it boils down to who the person is that's making the hiring decision that day, what mood that person is in and how well you are able to fool them into thinking you're a guy they can spend the month with. Just play their game, jump through their hoops. If you do everything right, hopefully they'll like you enough to hire you.