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This becoming a common phenomenon in my area, with the result that
I have lost one regular job and numerous one-time gigs (I know that
this is the reason because I ask bluntly).  If the trend continues, it will
no longer be possible to make a living as a Raks Sharki performer in
this area.  
Why do some dancers perform for less than the going rate?  Here are some of the possible reasons:

The dancer thinks she is not good enough to get the regular wage.  This is a problem of self-confidence.  If a dancer is
good enough to be hired at a club, she is good enough to earn the going wage.  If a dancer is not good enough to be hired,
the clubwouldn't let her perform regularly at all: the club doesn't want to become known as the club with lousy dancers. To
a restaurant, the difference between $60 and $40 is only one customer, two at most.  Imagine a club saying "Well, the good
dancers draw 20 people to the club, so we pay them $60.  But you only draw 19 people, so we'll pay you $40."

The dancer thinks the club can't afford to pay the going rate.  If that's actually the case, the club will fail and close.  (It's an
extremely common occurrence in the restaurant industry).  $20 a week isn't going to save a restaurant.  Remember, that's
one or two customers.  If the dancer draws anyone at all, the restaurant can afford to pay her the going rate.  If the dancer
does not draw anyone, there's no reason to have a dancer perform regularly.  Very small restaurants cannot afford to hire a
dancer, even if she does draw people and fill the place.   Such a  restaurant has a razor thin profit margin, and to stay in
business the restaurant needs to be drawing the same number of people anyway.

Many restaurant owners will say things like, "I can't afford to pay you $60 now, but we'll see if more people start coming
when we have a regular dancer.  If they do, we'll be able to pay $60."  Imagine if a business told a newspaper, "We can't
afford to pay for an ad right now, but run an ad for us, and we'll see if the ad brings in customers.  If it does, then we'll pay
you - starting then."  A real business will buy many ads on spec, and see which ones work (this is why you see "bring this
ad for an extra 10% off!").  They will stop buying the ads which don't work.  There is an advertising budget.  If there is no
advertising budget, the business is in such dire trouble already that it will fail and go out of business.  If a club truly can't
afford to pay a dancer on spec, the club is going to fail.  The vast majority of the time, the owner says that they can't afford
to pay the going rate because they know that they don't have to: some dancer will fall for it.

If a club can't afford to pay the going rate for a dancer, the club can't afford to have a dancer.  

Some dancers who perform for less than the going rate are deliberately trying to undercut other dancers.  This is not at all
akin to friendly competition.  This is a knowing, conscious attempt to lower the standard wages of Raks Sharki performers.  
That in itself constitutes unprofessional behavior.  Lowering the standard wages lowers the quality of life for all professional
dancers in the area.  Furthermore, in some areas, if the standard wages were much lower, it would actually be impossible to
make a living as a professional Raks Sharki dancer.  Dancers who undercut the going rate threaten to destroy the
professionals' livelihood.