Slim75,
Some of the issues here are, as you say, runway/taxiway suitability. However, that is only part of the issue with Fire rescue cover, weather/runway condition, approach aids and terrain/performance issues with a damaged aircraft and airfield opening times all contributing their own complications. Basic International protocols would see any airfield accepting any aircraft in distress (Mayday). However, the skill of a good flightdeck crew is them being able to decide if landing at a certain airfield with certain issues, is the best course of action in the circumstances. Also, a good ATC/airfield staff will advise an aircraft in distress if they see issues with their stated emergency divert.
BTW, you should find that competent crews have a comprehensive knowledge of this sort of thing!
