I can only see two reasons for the bitterness that people extend towards British Airways as a company and British Airways' employees.
1 - Anger at not being given a job with us (falling short at either stage of the application).
2 - Jealousy that British Airways staff are treated well by our employers, we're rewarded fairly generously for the work we do and the vast majority of us work for a company that we can be truly proud of.
What??? I've never applied to BA for a job and I'm never likely to, nor am I particularly interested in the pay and conditions of the staff. If I complain about BA (or any other airline) it's because I've received bad service and for no other reason. That being said, BA tend to be pretty good and don't give a lot of cause for complaint.