Image Copyright Heritage Auctions, used by permission
Some varieties are so minor that only the most dedicated collectors are interested. You might need a microscope and a lot of experience to even realize that a particular coin was a variety like that. It's also easy for inexperienced collectors to be fooled by PMD (post mint damage) and worthless MD (machine doubling).
There's a fairly easy to spot variety of 2014 cents that you might very well find in your change today. It's not as spectacular as the famous 1955 double die, but it is recognizable. The date and some other lettering are "fat". You probably could see it with your naked eye at least well enough to sense that something is wrong, but a low powered magnifier would help.
An example of that recently sold on eBay for $60. but as it's too early to say how many of these exist or what the market will ultimately bear, we don't know if that's a high price or a low price.
Resources and Books:
The Combined Organizations of Numismatic Error Collectors of America
Wexler's Die Varieties
Mad Die Clashes
The F.ind.ers report: A comprehensive guide to selected rare Flying Eagle and Indian cent die varieties
Cherrypickers' Guide to Rare Die Varieties of United States Coins, Volume I
Cherrypickers' Guide to Rare die Varieties of United States Coins, Volume II
The Authoritative Reference On Lincoln Cents
The Authoritative Reference on Lincoln Cents, Second Edition
The Lincoln Cent Resource
Note: All my coins are in a safe deposit box. I keep nothing in my home.
Contests and giveaways: http://coins.aplawrence.com/2014/05/contests-and-giveaways.html