By combining these two, 猥琐 (wěisuǒ) literally paints a picture of someone who is both lowly/cringing (猥) and petty/insignificant (琐). This perfectly captures its dual meaning of being simultaneously creepy and pathetic.
In Chinese culture, there is a strong emphasis on behavior that is open, confident, and honorable, summed up by the idiom 正大光明 (zhèng dà guāng míng) - “upright and open.” 猥琐 is the cultural antithesis to this ideal. It describes someone who operates in the shadows, lacks dignity, and makes others feel uncomfortable with their furtive energy. A useful Western comparison is the word “creepy,” but they are not identical. In English, “creepy” usually implies a potential, subtle threat. A person described as 猥琐 can certainly be threateningly creepy, but they can also just be pitifully so. Think of the character Gollum from The Lord of the Rings. He is conniving and malicious, but also physically hunched, cringing, and pathetic. His entire demeanor is the perfect embodiment of 猥琐. This combination of lewdness and wretchedness is unique to the term and reflects a cultural disdain for those who lack a dignified bearing.
猥琐 is a very common, informal, and highly negative adjective. You will hear it frequently in daily conversation and see it all over the Chinese internet.