Defending Myself Is Not Disrespect

I'm a short girl, and have been for quite some time. To make up for it though, I have loads of personality. I'm bubbly and fun, I'm open and honest; I'm pretty much the girl next door with a bit of a rebel edge thrown in to throw people off. However, I can be very...fiesty. Sassy. Cheeky. Borderline disrespectful, if I'm going by what my parents have told me.
While my mother defines it as a lack of respect (my father says a lack of social interactions with elders) I tend to rub a few of my parents' friends the wrong way. I say it becomes me; my parents raised me to be honest and to speak my mind. The respect part is given when it is earned, which I thought applies to everyone, but apparently not.
Apparently, if you have a few more turns on the earth than I do, you deserve my respect. If you hold a higher rank than I do, you deserve my respect. If my parents know your parents, you deserve my respect.
A prime example is one of my parents' friends. The person had spoken all of seven words to me in the time I'd known him, and yet told my mother that I was on the sassy side. I'm not saying he was wrong (not saying he was right either), but what I will say is me being a young adult at the time, he could've come to me and told me he thought I was a bit saucy. Instead of treating me like an adult and saying "Young lady, I felt that was disrespectful on your part," he told my mommy on me. Instead of giving me the chance to "talk back" to him as he'd seen me do to others, he went straight to what he felt was the source. And therein lies the problem.
My elders seem to think that "discussing" points of view with them is the same as "arguing" or talking back. My Gram moreso than my mother or father, told me that speaking my mind is always allowed, but in speaking my mind, I'd have to take whatever "fight" (read: "ass-whooping") I got with it and accept it. "When someone speaks against you," she said, "you have the right to defend yourself no matter who it is, but always do it with respect and tact because you are a lady."
As a full-grown (for the most part) lady now, I've taken this measure to mean stick up for myself in whatever tone I deem necessary, whether it be cheeky or sarcastic or whatever; I just need to be prepared for some backlash every now and then.