I'm looking for a word to describe someone who is so nice they impose on you. For instance, someone who, despite being asked to leave a room as it is, comes in and makes the bed and "cleans up." When confronted, says, "Oh, it only took a minute." Well-intentioned but defiant.
well-intentioned collins dictionary
If you say that a person or their actions are well-intentioned, you mean that they intend to be helpful or kind but they are unsuccessful or cause problems!
It depends upon whether or not you want a negative connotation. If you do, then some possibilities might be meddlesome (or meddling), do-gooder, or intrusive. If you do not want a negative connotation, then a single word might not be enough; you might need a fuller description to convey the notion that the person means well but unintentionally crosses the personal boundaries of others.
It may be too forceful a term, but I am reminded ever so strongly of the term 'smother' here.
1.1 Make (someone) feel trapped and oppressed by acting in an overly protective manner towards them.
‘it's time for you to leave the house—she'll smother you if you remain’
unctuous, according to Cambridge Dictionary:
"Unctuous people or behaviour expresses too much praise, interest, friendliness, etc., in a way that is false and unpleasant" 1
Another option could be overzealous, according to Merriam Webster:
"too zealous : having or showing too much zeal : excessively eager, enthusiastic, or fervent"2
Appropriate source attribution
1 "Overzealous." Merriam-Webster.com. Accessed March 20, 2018. https://www.merriam-webster.com/dictionary/overzealous.
2 (Definition of “unctuous” from the Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press)