The bottom line is, can you demonstrate your value to an employer? When you do house gigs, it gets tough after a while, because you are always there, and management gets used to the house revenue to the point of thinking it is normal, and not as a result of your entertainment skills.

Unfortunately, the only way around this is to simply up and play somewhere else a couple of times a year, for at least a month. Any replacement band or entertainer will do OK just on residual traffic for a week or so, but if you play another venue, and advertize well (and inform your regulars via social media) unless your replacement is top notch, they will follow you to the new venue, your regular venue's revenues drop off, and then you are in a position to come back with some clout.

While you may not get management to divulge their loss, you can usually get a waitress or bartender there (who are being treated as poorly as you!) to be honest about how sales have dropped.

But keep playing somewhere day in and out, whether treated poorly or not, you have very little to use for leverage. Let management stew in their own juices, let them see that you actually make a difference to their bottom line, you are likely to get treated better...