my experience was with a mentally ill person coming to the temple, doing the morning program and after getting madder and madder. So, we had to stop them from chanting japa. Weird, huh?
even if separated by any 'inserts' names such as ha-re will give benefit. there is no condition or contamination that can reduce holy names power, such as inpure place.
"i-have-to-tell-you-something-ram-ram-re-re-can-you-clean-the-pots-tomorrow-kishn-kishn-re-re" is not deminishing the chanting however if done without attention in offensive attitude it is. the word in padma purana is pramAda and is sometimes listed as an offence - it means however more - intoxication (the original meaning in Rig Veda and Mahabharata). ; madness , insanity (later then Puranic meaning); negligence , carelessness about (in our case chanting).
However in ANY case its better to chant then not to. Even with all possible offenses. MHO.