Is there any risk of illness from eating store-bought hummus?

Yes. Depending on how its ingredients were grown, harvested, and processed, hummus may be tainted  with salmonella, a food-borne pathogen. One potential source is the ingredient tahini, a paste made from sesame seeds. Hummus also may be tainted with the pathogen Listeria monocytogenes, particularly if it is processed under unsanitary conditions.
 
Pathogenic bacteria are of less concern with pasteurized brands than unpasteurized brands. Labeling may not indicate whether hummus is pasteurized, but pasteurized brands tend to enjoy a longer shelf life, as indicated by extended "sell by" or "use by" dates. They also may be shelf stable, meaning they do not require refrigeration.
 
Like other oil-based products, hummus can grow rancid over time once it has been exposed to oxygen. Exposure to heat, moisture, and light can increase the likelihood of rancidity. 
 
Hummus also can support the growth of mold or spoilage bacteria, either as a result of improper storage or proper storage over an extended period of time. 
 
Fortunately, proper storage and handling of hummus eliminates most risk of illness.
 
Source(s):
 Pritzker Law "Pars Cove Runs Business As Usual"
New York Times "Hummus Maker's Recall Widened"
Cambridge Journals "Sesame Seed Products Contaminated With Salmonella"