っぽい is typically used with adjectives and nouns to give your verdict on something based on how something looks or acts. Used with i-adjectives the final い of the adjective is dropped.
|A cheap-looking bag.|
Context: Regardless of the price, you think the bag looks cheap.
It can simply be added to nouns.
っぽい almost always carries a negative connotation and so the following is unnatural:
Here we would use 〜そう instead.
You may also see it used with the verb “to be angry” and “to forget”. Here we need the verb stem.
While not “proper” Japanese, young people may attach it to the end of the standard form of the verb as a sort of colloquialism.
|Something seems to be bothering her.|