Published October 2, 2021
Updated October 4, 2022 Smegma is a buildup of moisture, oils, and dead skin cells that collects between the foreskin and the penile glans in uncircumcised men. 
Intact America recently posted a blog entry from board member Marilyn Milos and executive director Georganne Chapin promoting this bodily substance. Milos and Chapin cited several supposed benefits - that smegma keeps the foreskin and glans soft and that smegma eases penetration during intercourse. The authors implied that smegma provides lubrication "for both masturbation and sex" and prevents dryness.  It's rather bizarre to see these two elderly women suggest that circumcised men cannot masturbate properly without artificial lubrication.
Tellingly the authors provided absolutely no scientific evidence to support their claims. A 2015 study in Canada found that circumcision did not affect vaginal lubrication nor a female partner's "pain during penetrative intercourse." 
Smegma is associated with certain infections. A buildup of smegma can irritate and inflame the penis, leading to balanitis. Smegma is more common in men with phimosis, which can lead to penile cancer. The American Cancer Society reports, "Smegma is more common in men with phimosis, but can occur in anyone with a foreskin if the foreskin isn't retracted regularly to clean the head of the penis... Most experts now believe that smegma itself probably doesn’t cause penile cancer. But it can irritate and inflame the penis, which can increase the risk of cancer. It might also make it harder to see very early cancers."  The Intact America authors pretend that these adverse effects don't exist.
Circumcision opponents seem to have a schizophrenic relationship with smegma. On the one hand Milos and Chapin imply that smegma is easily removed simply by washing the genitals with plain, warm water.  (However many women have reported that washing the penis has little to no effect on the unpleasant odor that accompanies smegma.) On the other hand, they claim that smegma is essential for lubrication and ease of penetration. In reality a female partner provides the lubrication for smooth penetration.
So which is it: Should smegma be retained or removed? Confused intactivists can’t make up their minds.
Urologist Dr. Rena Malik explained that an uncircumcised man must wash his foreskin every single day.
"Every single day when you're in the shower you need to pull back the foreskin and clean underneath the foreskin. The reason for this is because a certain substance called smegma can build up underneath. It's a yellowish substance that grows underneath the foreskin that can kind of build up in that area if not cleaned correctly. So when you're in the shower you pull back the foreskin ... and then go ahead with your finger and clean around the rim of the glans to make sure that it is clean and there's no smegma building up. That's because buildup of smegma can lead to recurrent infections, [which] is actually a risk for penile cancer." 
 Mario Abad; "What Is Smegma? This Condition Is Actually Pretty Common"; Men's Health; July 26, 2018
 Marilyn Milos RN and Georganne Chapin; "'Do You Know' About Smegma?"; Intact America; September 20, 2021
 Jennifer A Bossio et al; “You either have it or you don’t: The impact of male circumcision status on sexual partners”; Canadian Journal of Human Sexuality; 2015
 "Risk Factors for Penile Cancer"; American Cancer Society; Last Revised: June 25,2018
 Dr. Rena Malik; "Are you cleaning your penis correctly? It could save your life!"; Rena Malik M.D. YouTube video; September 2, 2022