I doubt if either is true
If your vent were blocked, the tank would pressurize...you'd feel major resistance when you flushed, and wouldn't be able to pump out. And it's highly unlikely that a hose connection is loose. The symptoms sound like you have two separate nd unrelated (except that they both MAY be related to the sanitation system...but maybe not) problems...and curing one won't necessarily cure the other: 1. odor in the tank coming out the vent when the head is flushed or the boat rocks, and 2. odor from a different source inside the boat. Putting vinegar down the head won't confirm or rule out permeated hoses.Before you do anything, read the articles in the HM forum reference library (on the right hand side of the forum homepage), especially 3 of 'em: Head Related Odors, Holding Tank Odors, and Boat Odor Isn't ALL in Your Head. They'll tell you the possible sources and cures.