In recent fights i've seen people using "He's been out for a while" or "He's had a long layoff" as part of there reasoning to pick against a fighter, but if a fighter stays dedicated in the gym and has decent sparring partners wouldn't it be safe to say that spending 36 minutes (or less) in a ring more recently then your opponent doesnt really matter when predicting a fight. I'm sorry I just don't really buy into ring rust.
look at vitali klitschko, it was even better for him to have a long break to come back healthy and fresh
No it was not, it never really is, he is just lucky his opposition is weak.Vitali is not as powerfull as he was before his layoff, it also kept his legacy from growing.
It depends on the fighter though it usually affects timing and overall sharpness in the ring. I'd say a long layoff is bad for anyone though.