That's a difficult question. Generally, if a question can be solved by pointing at a page on which the requested rule can be found, then this should be done. Quotes should be posted only if there is a question about a certain interpretation of the rules, which requires lawyering about the precise choice of words by GW. If someone obviously doesn't own the codex or rulebook and he just tries to leech rules from the web in order to save money, then he of course shouldn't get an (from his point of view) useful answer at all.
Examples:
"Could you please tell me the stats of unit XY?"
Answer: "No, sorry, that's copyrighted information and we may not post it. You can read these stats in Codex ABC, page 666, just have a look into it in your local store."
"Can i use the tyranid mutable genus tables in order to create gaunts with both wings and leaping?"
Answer: "No, as written in the mutable genus rules on page 39, gaunts can have only one movement biomorph."
On the other hand, if a close look at the rules is necessary, then such a thing would be tolerated by GW:
"In the skimmers moving fast rule, it says that "shots" will hit less important parts of a skimmer and therefore it can be only glances if it moved fast enough. Does this also apply against close combat attacks?"
Answer: "BBB page 89: <a quote which says that close combat included point blank shooting and grenade lobbing, in order to show that the word "shot" doesn't limit that rule to shooting>, and a few words as explaination"
In this case, the question couldn't be answered without quoting, because there is no specific rule which can be pointed at, it requires some interpretation of specific passages of other rules which need to be quoted in order to show what is used as an argument.
jwu