Home made ranch dressing has bubbles. Is it bad?
For some background: On our site, only official, stringent food safety is on topic. Any further considerations are considered not suitable for discussion here. 

From the point of view of food safety, the question "is it bad" does not exist. The only difference that can be made is between safe food, for which there is absolutely no doubt that there is nothing wrong with it, and not safe food, which includes anything from "formally not OK even though 99% of people would eat it" to "I see the maggots crawling in it". There are no further distinctions made, and this one distinction is based not on the actual chance of the food making someone sick (which is usually not calculable) but on what one can prove about the food's chance to make someone sick. 

Based on this (admittedly very unintuitive point of view), your dressing, your mayo and your milk are all unsafe. I am not entirely sure if the sour cream may fall under some exception. The reasons: 


all food you prepared, and all food you bought in a hermetically closed container and opened, is considered unsafe after 3-5 days from preparation/opening, unless it falls under a more specific rule. (There could be one for sour cream, since it is fermented). Your food was opened/prepared 7 days ago. 
also, the moment you notice something which you don't know if it is spoilage or not, you are required to assume it is spoilage, which makes your food unsafe. So, it doesn't matter what these bubbles are - if you don't know for sure they are OK, they are considered not OK, no matter on which day it happened (this precedes the time-based rule). 


I know you were probably expecting a different kind of discussion, but it is not something we can provide.