You wouldn't buy a car or a house without asking some questions about it first. So don't go buying into someone else's data without asking questions, either.
Okay, you're saying... but with data there are no tires to kick, no doors to slam, no basement walls to check for water damage. Just numbers, graphs and other scary statistical things that are causing you to have bad flashbacks to your last income tax return. What the heck can you ask about data?
Plenty. Here are a few standard questions you should ask any human beings who slap a pile of data in front of you and ask you write about it.