Are there downsides to speculative applications for academic jobs? Speculative applications, i.e. application without a job announcement being published, are common (well, at least normal) in non-academic jobs. But I am not sure the situation is the same in academia. Somebody has suggested me to send speculative applications to different departments for teaching or research jobs. I was thus considering the pros and cons of this type of applications.

The pros are almost evident (more exposure). However, I worry about potential downsides. In particular, how would potential employers look at such an application? Could it make me look bad? Is there any other downside I haven't thought of?
Here is my standard advice to PhD students applying for academic jobs:


First, look for departments that are advertising for faculty in your subfield.  Apply there.
Second, look for departments that are advertising for faculty, but not in your subfield.  Apply there anyway.  There is no way to tell from the advertisement whether the listed fields are requirements, preferences, or mere examples, or if they just recycled last year's ad without reading it first.  (Yes, I have seen all these alternatives.)
Third, look for interesting departments that are not advertising for faculty.  Apply there anyway.  There is no way to tell from the lack of advertisement whether they are really not hiring, or they just aren't advertising widely, or they just haven't posted their ad yet, or they thought they posted the ad but didn't.  (Yes, I have seen all these alternatives.)


Before anyone objects: Obviously, I'm not talking about your department.  Everyone  knows that your department's advertisements are precise, timely, and highly visible.  I mean other departments.

Of course, if you're thinking of applying to any department, whether they're advertising in you subfield or not, it's a good idea to contact someone you know in that department to find out what they're really looking for.  If your contact says "No, really, we aren't hiring X," you can save yourself the trouble.  But if you (or your advisor) don't know anyone well enough to ask?  Fire away.