How much of a handicap is lack of consistency

[Western]

This site in question has changed hands more than three times in the last three years and multiple people have worked on it. Although all parties have had similar visions, they've executed them in ways that are subtly inconsistent. This is a local directory/business review site.

Some aren't visible to users (who aren't picking through code), some are.

Invisible inconsistencies include absolute URLs and relative URLs used interchangeably, small differences in file structures...

Visible inconsistencies (which are far greater in number than the invisible inconsistencies):

Phone numbers :
[phone]
555-555-5555
555.555.5555

Biz listing:

Name, Address, Phone Number
Address, Phone Number, Name

I realize the disadvantages associated with this include being crawled and appearing in SERPs in ways that may be counterintuitive to a visitor...etc...and the site will be redesigned (the only reason for the this post is to help establish a priority list for the site).

Is Google taking into account the lack of professionalism indicated in these visible inconsistencies?

[tedster]

Not in my experience - and I have several sites that show these kinds of inconsistency. Users are more likely to notice these things. Even if Google did notice in some way, these factors really don't affect relevancy. They would be the weakest of signals. So my guess is that Google doesn't even bother.