What absolute out of date bollox!
This article is identical to one written nearly twenty years ago, so is hopelessly out of date. For a start, no US carriers (who the article implies are the most likely targets) offer a First Class service any more........they are all "J" class or Business Class to you or me!
For a start, the only Transatlantic operators offering genuine First Class are BA and Air France, however, judging by how few commercial clients are actually paying for First Class, it remains to be seen for how much longer these carriers will run with it! Neither BA or Air France will upgrade 2 classes (or 3 if BA has World Traveller Plus fitted on the aircraft) unless you are able to offer significant commercial advantage (eg a Head of State who will be televised worldwide descending the stairs with the airline's logo emblazoned proudly!)
As a Customer Service Agent, I do not hold it within my power to offer upgrades. Merely to indicate someone who "may be suitable" in the event that a flight is heavily overbooked. There is a dress code - preferably shirt and tie, no jeans and no trainers. (If you're paying for J class, you can wear what you like, if we're upgrading you, you've gotta look the part!) Even then, there's no guarantee.
Whilst it would be nice to have a few 100$ bills every day for putting SFU comments in, my job is worth far more than that to me, and I wouldn't ever accept bribery! A smile of thanks is reward enough!