Alarm for invisible characters?

I recently copied a list of names from a webpage to Excel and started comparing them to another list, but got no matches. Turns out the imported list had a string of nonbreaking spaces in front of each entry that didn't display in any way in Excel, it hides them. Is there any way to get Excel to throw an alarm up for invisible characters? In an ideal world, it would also warn you about regular spaces when you paste date/numbers. 9 out of 10 times, people don't want them. And if not: I searched both on Bing ( 😄 ) and Google for a place to submit an improvement-suggestion, but couldn't find an address/page?