I understand that 適当【てきとう】 can mean both "appropriate" and "whatever/vague". How do you know 適当な人を教えてください means "please inform me of the appropriate person" as opposed to "please tell me about whatever kind of person you want"? Is this determined entirely by context?
Because 加減【かげん】 means "condition", いい加減 seems to be "good condition" -> only the "reasonable" definition comes naturally. Yet using it to mean "irresponsible" is standard (いい加減に仕事をするな), except when you tell people いい加減にしなさい. Where did that come from?
I saw this question in 日本人の知らない日本語 but no explanation was given. I am living in Japan but none of my Japanese friends can explain it either.