Dis-lex-sic from what I understood from your post, your main gripe is new users signing up to see what deals they can get on a new car. You also state that these members haven't contributed anything before or after such posts. If they haven't bought an IS yet what possibly can they be contributing beforehand? And if they just inquired about price, it also stands to reason that even if they did end up buying one, it probably hasn't been delivered yet. Personally I don't see any problem with someone trying to get the best deal possible on a vehicle purchase. I've purchased enough new luxury/exotic cars over the past few years to know how unscrupulous some dealers can be in misrepresenting the deals they are offering. Granted that there's definitely some honest folk out there but the reality is that it's in the salesman's best interest to get as close to RRP out of you as possible.
I only signed up to this forum recently after purchasing my IS350 and my first post was to give an indication of what I paid for my car in WB.47's thread. There is nothing wrong at all in helping someone get the best deal possible on a new car although I agree that asking another member for a sales contract is a bit rude. But again, if personal details and the VIN was blacked out, this wouldn't be THAT much of an issue either. This knowledge may enable someone with the purchasing power to buy an IS350 over an IS250 for instance. I think the 59k on the road I paid for my IS350 was a great deal and was done with very little negotiation. I had other dealers telling me that 65k is their rock bottom price for the exact same car and were adamant that they were going to lose money if they sold it below that. Obviously when you hear such mis-truths you begin to question the integrity of some salespeople. Again I have no issue at all in others getting a great deal on a new car using the advise that members have provided. In fact if you visit some other forums such as VWWatercooled they have spreadsheets you can download which list what members paid for their cars and what options were ordered and % discount over RRP.
The only person I can imagine that would disagree would be a salesman who stands to lose if everyone was able to get the best price possible. However, I don't think anyone here is averse to saving money on a new car... except for the person who sets to gain by taking as much of your hard earned as possible