Smudging is a huge staple in the witchcraft/pagan community. I recently engaged in a debate with someone over whether smudging in the modern day was a good idea. I did a ton of research for that conversation, so I thought I'd compile some pros and cons here for reference.
Pros:
Smudging is an excellent way to clear negative energy
Sage/rosemary/other herbs can be used to draw specific positive energies
Great way to clear malevolent entities
Makes you feel witchy, especially if you're a beginner
As with most popular witchcraft tools, it bolsters the witchy aesthetic.
Cons:
Originates in Native American tradition, and when used by non-Native peoples is sometimes considered a stolen tradition
Is an EXCLUSIVELY Native American tradition, and if you don't do your research you can misuse it
Sage = energy bleach. If you don't use another herb of incense after, bad energy can come back in with reinforcements.
Sage kinda smells like marijuana (or so I'm told)
Incense can be harmful to animals
I'm not a pro, so take this with a grain of salt. May the blessings of Olympus fall gently upon your heads, readers!
Yhis can be very heavy to discuss. Personally, I believe smudging in the way that native Americans do, and calling it smudging, is offensive to enough forst nations people that I avoid it. Trying to recreate cultural rituals of people who my ancestors suppressed and killed doesnt sit right with me. However, smoke cleansing and burning insense and plants has merits, and i feel as long as you are creating your own ritual and ensuring that you arent fumbling your way through a recreation of something sacred to a marginalized culture, its ok. However sage is also becoming endangered, so I try to encourage people to use alternatives. Again this is my personal opinion and I am open to new information, however I am more sensitive to opinions of those who have cultural ties to the tradition.