Some idioms are confused in the speaking; others just in the spelling. The following idioms are usually pronounced correctly, but they are often misspelled in writing.
1. waiting with bated breath
The word bated in this expression is often misspelled “baited.” For example, “We’re waiting with baited breath to hear if Rosie O’Donnell is officially coming back to daytime screens.”
The word bated is from a shortening of the verb abate. “To bate” means “to reduce, to lessen in intensity.” The expression “bated breath” is the only survival of the word in modern English. Read more here.
2. lo and behold
People use this to mean something like “and then see what happened.” The idiom is frequently misspelled as “low and behold.” Lo is an old form of “look.” Read more here.
3. pore over