bnt - I very much echo your sentiments on those who design websites in a way which tries to deliberately raise the Google page rank score more than would be reasonable.
When booking a room in a hotel, I prefer to book directly with the hotel. Not only does it avoid the risk of communication screwups (has he paid the bill in advance or hasn't he) but particularly for small family-owned hotels, it means the family doesn't have to pay the commission. The problem I had was that when searching Google for a hotel, I ended up getting huge numbers of generic hotel booking sites with a high page rank, but the hotel website itself would then end up somewhere far down the search ranking, necessitating a long and painful trawl through various websites to see which was the genuine hotel website rather than a company that claimed to be the local expert for hotel booking. Google has now changed this for hotels (presumably hitting the middlemen where it hurts), although the problem still remains for restaurants.
I fully expect an airline to give plenty of bluster... but in terms of action, I'm a little puzzled as to what they can effectively do. I know that some airlines impose a 'your session has been locked for 20 seconds' screen now and again, but this is not a major deterrent. I have a dynamic IP - continuously blocking new IP addresses doesn't seem (at least to me) terribly effective against a screen scraper who keeps using a new IP - furthermore this also blocks out other potential unrelated customers. Further, I won't be using this data for commercial or non-personal purposes, and will not be posting this data on another website or supplying to a 3rd party - I'm not stupid or daring enough to encourage an airline to sue me. The only money I make will be my getting personal access to the 'loss leader' fares on which the airline has tried so hard to be opaque and bury.