DemocraticUndergroud.com is a community of Democratic party supporters who feel that the internet already has enough sites that host messages of hate, disingenuous argumentation, smears, trolling, and/or outright lies. Therefore, all anti-Democratic and anti-liberal trolling is banned, regardless of whether that hate comes from the far right or the far left. Most of the reviews here reflect the anger and frustration that individual trolls have at the DU refusing to host their polemics.
Within those modest guidelines, the DU has a lively discussion of analysis, news of the day, etc. There are disagreements, most which get resolved amicably. The vast majority of regular Democrats are perfectly comfortable there; moderation is considerably lighter than you find on most political subreddits.