Do reviewers become biased about research papers written by authors of a previous low quality paper? In single blind paper submissions, reviewers can see the author names and affiliations. Suppose two papers are submitted in a conference, one of them is fairly well written and the other one is a low quality paper. Also, one or two authors are common in both the papers. If both the papers go to same reviewers for review and reviewers review the low quality paper first, do they become biased while reviewing the fairly well written paper? Do the chances of selection of the good paper become less?
I would distinguish between two papers in parallel (as in your example) versus a history of bad papers.  

If I'm seeing a good paper and a bad paper that share an author, and I don't yet know that author well, then the bad paper probably won't affect my opinion of the good paper too badly (unless we are talking really embarrassingly bad).  I'll have a mixed opinion, but I'm still forming it.

On the other hand, there are certainly some authors who have built up a history with me such that I see their paper and think: "Oh no, I hope they've learned from last time."