Question: Assuming the process isn't double-blind, do you often look at other work by an author out of curiosity, and do you think this should influence your decision on a paper?

Answer: 
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> As a reviewer, is it appropriate to look up other work by an author and factor that into your decision?
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**No, this is not appropriate.**

I would argue that this is one of the exact things double-blind review is supposed to prevent. In the context of double-blind reviewing I have heard the following scenarios / arguments, all of which I feel are invalid:

* *"If the authors have a history of writing bad papers, I should be more critical."* No, you shouldn't. You should judge the paper in front of you, not previous papers the authors have written.
* *"If the authors are more famous than me, I am nervous that my criticism may be wrong."* Uh oh. If you are unsure, don't criticize. If you *are* sure, criticize even if the authors are the most famous in your field. And don't worry, even the best researchers (and their students) get things wrong.
* *"If the authors have a history of academic misconduct, I should be more critical (e.g., not give them the benefit of doubt if data is not entirely provided)."* I understand the sentiment here, but I would argue that you are overstepping your role as reviewer once you start judging the trustworthiness of researchers as people, and then apply different standards to the manuscript based on your assessment. Given that much reviewing in the sciences in practice operates on a certain basis of trust, and given that we also know that a minority is abusing this trust, there is likely a level where we need to take prior behavior into account, but individual paper reviewers are almost certainly not the people who should be making these decisions.
* *"If the authors are presenting many similar papers (or many papers building on top of each other), we should rather reject to prevent salami slicing"*: Ultimately, if a paper would have sufficient contribution if written by somebody else, it should also have sufficient contribution if written by the same authors. Conversely, if the contribution is very minor in comparison to existing work it should be rejected independently of who exactly wrote said earlier work.
One of your jobs as reviewer is to determine the novelty of the work. For that you should acquaint yourself with what was known prior to it (if you are not already very familiar with the field), both due to the work of the same author and of others. To that end it can be useful to browse the author's earlier work.

It would *not* be ethical to let your judgement of the author's earlier work influence your opinion on the quality of the work under review just following the "logic" that the previous work was "meh", so this can't be any good either, or that this is such a famous author that the work under review must surely be great.