I don't think that pay raises for congressmen and senators is necessarily a bad thing. I'm sort of torn about it.
Salaries are currently $165,200. I think I'd rather have the Senator who really needed the extra $5,000 per year than I would the Senator who doesn't give a damn about what he or she is paid.
Why? Well, for one thing, I think people that don't have millions may have thought before about tax policy; they might realize that they've changed their behavior because of taxes; they're going to be more close to reality.
Look at who the multi-millionaire Senators include:
John Kerry [married into money that had married into money]
Herb Kohl [interited from Kohl's stores]
Jay Rockefeller [inherited]
Dianne Feinstein
Maria Cantwell [earned it in a dot-com-bomb]
Edward Kennedy [inherited]
Mark Dayton [inherited money from Target stores]
Bill Frist [started HCA, a for-profit hospital chain]
I guess the main reason to be against higher salaries is that congress and senators should be citizen legislators, not career politicians. So maybe they work a few terms as a senator then go back to the private sector.
But the Senate is increasingly becoming a club for millionaires, which I don't think is a good thing. I think another reason for all the millionaires is campaign finance reform.
More a reason for term limits. Serving in congress was meant to be a duty, a short-term duty. In and out. Not a career.