There are so many factors that go into credit scoring and like the previous poster mentioned, good luck getting some info on that.

In the spring of 2008, I refinanced 2 mortgages, and after the mortgages closed, I applied for several credit cards (high limits from credit unions), etc. My score dropped about 40 pts from 720-760 (742 mid bureau) but my score almost fully recovered within 6 months. The only reason my scores didn't fully recover were that some old positive trade lines dropped off due to it being over 10 years after the accounts were closed. That dropped my AAoA (average age of accounts) alot. That affects FICO's.

I won't be able to refinance my rentals in the near term due to the 70% drop in values from 2006 to 2010. I am keeping them because I want to be responsible and the rents pay the mortgages.

Back to the topic at hand. The inquiries (my estimate) only dropped my score about 3-4 pts/inquiry. I just applied and got approved for 2 AA credit cards @75K bonus miles each. With those bonuses, it is IMHO worth taking a few point hit on FICO to get those cards. (of course, I assume that one doesn't need to buy a house or refinance--in that case, it may be prudent to hold off applying until after closing).