don't use double quotation marks ("like this") in your tags if you're talking in the tags- it'll format it wrong and mess up what you're trying to say by taking whatever you put in the quotes and kicking it to the front of your tags. so for example, if you're trying to say
#you'd have to be an idiot to believe that "there's no such thing as greenland" #smh
it will format as
#there's no such thing as greenland #you'd have to be an idiot to believe that #smh
if you want to use quotations in the tags, i would recommend just using single quotes instead ('like this')! i'm not sure why tumblr does this, but it's very odd and it's been a problem for years.