I find the term "
I guarantee" used in that way sound very absent of IQ. You are unable to guarantee anything, you offer nothing in case of failure, and therefore should not use the term. It's generally used by someone trying to add substance of proof to some point that actually has none.
I find that it is an immediate turnoff when I hear it just like when someone has the gall to say "
Trust me". For someone to say "
Trust me", it is the sign of someone who will repeatedly let you down or rip you off. Trust is earned, not handed out like piece of gum.
Thanks for allowing me to add 2 points of IQ today.