I'm a journo, too, and I've been writing full-time about aviation and aerospace for 23 years, and a little time before that as a part time freelance.
I'd agree with Airsound as to the occasional value of spotters, though there's is a hobby I find it hard to understand.
I would absolutely disagree as to the credibility of the Guardian in this case - the journalist concerned seems to have been running a pretty cynical and unscrupulous one man war against BAE (think of BEagle with a pen, and without the sense of fun).
And whatever Ms Corbin's merits, to front a Panorama whose primary focus was a military aircraft procurement, I would have though that some grasp of military aviation would have been a help. She had a great manner on camera as she compared the prices of RAF Tornados (£16m) and RSAF aircraft (£21m) and paraded herself between two badly made Airfix models and the Tornado in the RAF Museum. She took no account of the support/spares/weapons included in one price, the inflation which increased prices between one contract and the other, nor the fact that the RSAF proce was an average based on GR1s, 1As and F3s.
Moreover, the use of words like bribe is pretty emotive. Payments to middlemen and facillitators are routine in the Middle East, and these payments were authorised by the MoD, which makes them seem rather less sinister than 'slush fund payments' made under the table by some corrupt company.