Okay you have no idea what communism is and you are WOEFULLY misinformed about what happened in both Korea and Vietnam. But let's forget about communism for a second, even if it is a "disease" what the Vietnamese people, my people, wanted was primarily independence.
Helping an ally? Read the Pentagon Papers. That was never a goal.
FIGHTING FOR THEIR FREEDOM? What do you think the North Vietnamese and Viet Cong forces were doing? You realize Indochina was COLONIZED (not administered) by France for about a hundred years prior, right, and the Viet Minh fought a successful war of liberation during the 50s. "South" Vietnam never asked for US help, "South" Vietnam didn't exist until Western imperialist powers decided to create it after the First Indochina War. Okay so now they more or less kicked the French out and the US decides to wade in, what do you think happened? The Geneva Conference TEMPORARILY divided the country in two and set a date for elections to determine the eventual governance of the country. Yes, Ho Chi Minh and his allies would have won it with or without electoral fraud, before you go there, he was very popular and seen as a great liberator (which he was). But that didn't happen, thanks to Ngo Dinh Diem, who was a US puppet.
You know what the Vietnamese asked the US for? Independence from France. Ho Chi Minh himself petitioned Woodrow Wilson for independence, and the Viet Minh actually worked with the OSS during WWII to stymie the Japanese occupation at the time. They did this because they thought the US would actually help them gain independence after WWII, but they were very sadly mistaken. That is why the Vietnam War happened, because the US let ideology and racism get in the way of intelligent global politics. If you think the US was right in trying to curb the power and influence of the Soviet Union and/or China, then you should adopt the position that the US should have helped out the Viet Minh and allowed democratic elections after the Geneva Conference. Vietnam and China actually went to war in 1979, they were in no way friends. US policymakers failed to differentiate Vietnamese politics with Chinese politics, like you do, when you talk about "communism" being one monolithic bloc that the US opposed.
Allies? Please. The Viet Cong were SOUTHERN Vietnamese communists fighting alongside the North Vietnamese forces. People from all over the country wanted independence, it was not a case of the aggressive North trying to invade the poor, democratic South. Again South Vietnam wasn't even a thing prior to the Geneva Conference. It isn't like people from the north and people from the south in Vietnam are different people, we have slightly different attitudes, a different accent but we're still Vietnamese. We're about as different as an American from New York and an American from Texas, ie, hardly at all.
As for Iraq, come on. The Coalition made up the reasons for going to war and fucked everything up in the region, which you don't dispute. I mean if this is your model for effective international policymaking, wherein a country that could very much leave well enough alone, instead of interfering in shit that causes way more problems down the line, then I just gotta laugh.