Have you ever gotten a 597 signal report after putting a lot of time and effort into building that new rig copied from an old (or really old) issue of QST? What is the other station hearing? More than likely they aren't familiar with the definition of a T7 signal (which to many of us sounds fine). Maybe it just sounds different or maybe it has chirp or maybe it sounds like a buzz saw the morning after a big party.
The first thing I do is check my signal in the shack receiver, but lots of times I'm overloading my receiver and I sound like that buzz saw. Is this really what others are hearing? Maybe being so close makes a minor problem sound worse than it is.
The next step is to have a friend a few miles away listen to you and, possibly, hold a phone up to the speaker so that you can hear your self. This can be real helpful but lots of times I need a more complete listen.
As a final check I recommend taking advantage of one of the many web based radios available all over the world. Link into one of these, turn on your own computer speaker, set the frequency/mode you wish to test and then transmit. Given needed propagation you can listen to yourself and the waterfall display helps you see what your signal is actually doing.