Pronouncing all "Rs" as "Ds"

[wafflestomp]

I learned this from a Spanish teacher a few days ago... I am a little hesitant to trust what she says because of a few issues (she taught the conjugation of the vosotros subjunctive entirely wrong and actually came in the next day and apologized, she also used the word "nieta" for "niece") so as you could probably figure I am hesitant about this. From some practice with Rosetta Stone's pronunciation checks, it seems to always work. For example, pronouncing "Para" as "pahdaa" or "encimera" as "encimedda", but I just want to know if this is something you really want to rely on and if it is true or not.