Taboo Game Question/Rule

2 examples: The word you are trying to get your team to guess is “PEST” and someone says “PESTICIDE” or the word is “FAME” and they guess “FAMOUS”. Does it count considering they technically SAID the guess word as part of their whole word? You have to say PEST to say PESTICIDE. Why does it matter what other words come before or after the word you are tryin to get them to guess? Example: If the word was “SALT” and they guessed “SALT AND PEPPER” would that not count? They said SALT.