For my part, I don't think there's anything particularly racial about these ethics investigations; it's just that long-term incumbency breeds this kind of corruption. Indeed, if you take a quick look at each of the congresspeople under investigation, you'll notice that most are long-serving incumbents. Simply put, when you're isolated from credible challengers, you have no electoral incentive to stay clean. In the long-run, the best way to combat corruption is to create as many competitive districts as possible so that incumbents do not become complacent.
For the record, I have yet to meet a white person (male or female) named Jamelle. That's definitely a name my people use.