EXCLUSIVE

Warren Sapp wasn't exactly Mr. Congeniality at the NFL Network -- with a whole bunch of employees telling TMZ Sports they're GLAD he's gone ... because he was a nightmare to work with.

We broke the story ... Sapp was fired from his gig as an analyst for the NFL Network after he was arrested for soliciting prostitutes in AZ last Monday.

Now, after speaking with nearly a DOZEN current and former employees ... everyone is telling us the same thing -- GOOD RIDDANCE!!

In fact, the people we spoke with ... ranging from low-level people all the way up to big shots ... told us there was an unofficial "Sapp Disclaimer" when it came to interacting with the Hall of Famer.

Among the highlights:

-Don't look Warren in the eyes (seriously).

-Introduce yourself, but DO NOT try to befriend him.

-Call him Warren. NEVER call him "Sapp."

Of course, there are Sapp supporters ... but even they couldn't really defend the guy.

As one person put it, "I know certain people [at the Network] complained about the guy a lot but overall he was always cool ... just unpredictable."

Another person told us, "Warren has had one too many chances to get it right, and it just didn't work out for him. We all wish him well in the end."