Using a starter kit suitable for mouth to lung vaping , most liquids have very little odor output. Particularly with Menthol and fruit flavoured Liquids. However Tobacco liquids can have a slight smell to them depending on the formulation. Most standard tobacco's are not offensive to bystanders. However more specialized blends can produce stronger smells.
Sub Ohm or more specifically, direct to lung inhale style devices (that produce vast clouds) produce noticeable smells of the flavours being used in them at the time. Very simply put, the more powerful the device the more scent it's likely to create for bystanders.