Being a lawyer is all about believing in your client and giving them every benefit of the doubt. That said, I'm sure many do have to defend obviously guilty parties.
Everyone has the right to an attorney, and a fair trial. So I don't think a lawyer playing their part should be seen in a bad light.
I used to think like you do, OP, but lawyers are an important part of society and I don't think that level of reductive thinking is entirely fair. I even said something similar to what's in the OP once in high school, that lawyers are paid to lie, and it turned out the girl across from me's dad was a lawyer. I didn't feel bad at the time because I thought I was right, but the older I get, the more I realize how shallow my thinking was.
That said, I would never be one. Too boring.