你(subject)好2好3待在家裡 is natural but 飯(topicalized object)好2好3吃 meaning 飯好好地吃 is unnatural for me. And I agree with Brofeelgood that 玩具好2好3玩 ≠ 玩具好好地玩, 電影好2好3看 ≠ 電影好好地看, and 这首歌好2好3听 ≠ 这首歌好好地听. 「玩具好2好3玩，不要放到嘴裡吃」 sounds awkward or confusing to me. If I have to keep 好2好3 as an adverb of manner in a sentence with a topicalized object, I would add an element capable of disambiguating its meaning, for instance, 得dei3 in 「玩具得好好玩，不要放到嘴裡吃」, 著 in 「電影好好看著，別打瞌睡」, duplication of verb in 對策好好想想, and 地 in 这首歌好好地听.
我一般都是hao3hao1，基本不会念hao2hao3，类似的还有： 慢慢man4man1, 早早zao3zao1, 而且第二个字要儿化，第一个字可儿化可不儿化。
Indeed, when there is r-coloring, it is always 好3好1儿 for me. 好2好3儿 sounds strange to my ears. I think the reason I would sometimes say 好3好1(儿) is that there is a clear semantic change: from 好2好3地 "well, nicely, properly" to 尽情地 (e.g., 咱們可得好3好1喝一頓酒 vs. 大聲做啥, 有話不能好2好3說) or 平白無故 (e.g., 你瘋了麼? 好3好1來這儿鬧事, 找死啊), and the tone change is to signal the semantic change.
I always say 缓2缓3, 傻2傻3, 久2久3 and 早2早3, and never 缓3缓1, 傻3傻1, 久3久1 and 早3早1. Although I think I've heard 早3早1 somewhere (I guess on TV), it oozes a strong dialectal flavor to me.
Re: Adjectives (e.g., 甜甜, 软软, 长长, 小小年紀, 小小心意).
I always say 小2小3 and never 小3小1, always 软2软3 and never 软3软1. In fact, I cannot think of any adjective that I would make a tone change like 好3好1.
