Google has a tendency to match your exact match keywords to a wide range of search terms, not all having a similar meaning or intent as the original keyword.
One way to auto-detect when search terms may be too different from the keyword they were matched on is Levenshtein distance, which is simply the number of characters that have to be changed, added, or deleted to turn one string (word or group of words) into another.
The Levenshtein distance will trigger a warning based on keyword string length as follows:
< 16 characters = distance of 3 or higher 16 - 20 characters = distance of 4 or higher > 20 characters = distance of 5 or higher
It will also ignore word order. So "trueclicks pricing" and "pricing trueclicks" are considered to have a distance of 0. We know word order can make a difference (especially in the travel industry), but we'll ignore it for this purpose.
While Levenshtein is not ideal for detecting synonyms that are spelled very differently (like "amazing" and "incredible"), it is useful to quickly double-check if search terms with a high distance to their original keyword need to be added as a negative.