Unfortunately there aren't any bright lines in the law... it's ultimately going to come down to a judgement call.
However, adding a descriptive phrase or a logo to a conflicting mark will probably not eliminate the confusion.
One factor to take into account is "degree of care" on the part of the purchaser. In areas where the purchaser is assumed to have special expertise or perform extensive research prior to purchase, similar marks are not likely to cause confusion.
With consumer goods, the degree of care exercised when buying consumer goods is low. The consumer might just glance at the label, see a familiar word, and assume it's the same brand. So the examiners generally set a pretty high bar for avoiding confusion.
I generally advise people not to get attached to potential trademarks. If it looks like there are going to be hurdles getting it approved, pass on it and choose a different mark, unless you have a very strong business reason for a specific mark.