What's the difference between "怪しい" and "疑わしい"?
Apparently, they're similar enough that dictionary.goo.ne.jp has a guide for distinguishing the two words (along with two other words), but it's in Japanese and Google Translate doesn't do a good job of translating it.
As background, it's being used to describe an ad that had a stated requirement, but where it's suspected the creator of the ad had an ulterior motive in mind. "疑わしいアド" was used in my original version of an online post, whereas "怪しい求人" was suggested by a native speaker of Japanese.
I've just discovered that Wiktionary has some info on distinguishing the terms (order reversed for ease of reading):
怪あやしい (ayashii) implies something for which the true nature isn't known, and this uncertainty is a bad thing.
疑わしい implies something for which the true nature or quality isn't known, but that may be good or may be bad.
which is at least in English, but still seems a little confusing to someone who is somewhat unfamiliar with Japanese culture.