Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
If you visit a store that has their meat labeled halal or you visit a friend whom you know only eats halal meat, then you should not ask if the meat is halal or not.
Answering your question, Sheikh Mustafa Umar, President of California Islamic University, states:
It is necessary to balance between taking precautions to only eat halal (lawful) food and giving others the benefit of the doubt.
So if you visit a store that has their meat labeled halal or you visit a friend whom you know only eats halal meat, then you should not ask. You can safely assume that they are being honest and not deceiving you.
However, if you visit a store that does not label their meat, or you visit a friend whom you have a reasonable suspicion that they do not only eat halal meat, then you must ask. You should be polite, but not shy away.
Almighty Allah knows best.
Source: AsktheScholars.com