I may not be giving the current window a "fair shake" as I'm sure its a low end Pella or JW from Home Depot and does have a break in it, but having a loud living room makes the property undesirable. 

proximity to arterials,  property layout, etc.If  you put up a fence to reduce people entering and crossing your property from all directions,  and your building is in an area that has graffiti or street crime issues,  make sure its a chainlink fence,  or a low one,  or otherwise not an "attractive nuisance" that invites tagging or can hide undesirable activity.   

Mortgage interest is an undesired expense, but, it is a consequence of a loan, which is good, in the sense that you can hold a larger earning asset.

Clean up our society by eliminating the undesirables?

If one tenant is a very small part of the overall space and has a less desirable lease if the overall cap rate is good with available good loan terms then buyer might still go for it.If however your property is riddled with crappy tenants and crappy leases with fixed rents and heavy cost caps slanted on the landlord that can make your property very undesirable and hard to sell.You really need to know when negotiating these leases what the buyer is looking for with positioning to sell in your favor.

AMC has been wise to issue shares at these sky high prices but wouldn't it be wiser to buy their "undesirable", discounted theaters and do an OpCo - PropCo split; spinning of their real estate into a REIT refinancing some of their expensive debt as property level mortgages along the wayWould be a hell of a lot more tax efficient! 

@Lam N.Based on my experience think it could create some undesirable attention.

I feel she is now more focused on her commission than helping me avoid undesirable properties, thoughts?

Agree with Adam that very high HOA's make them undesirable as rentals.......

...but even then, 3 months does seem like a long vacancy if your property is in a major city. 3 months of vacancy probably indicates that A) the PM is not marketing the property correctly, or B) there's something making the property non-competitive (perhaps it's not as nice as other properties in the area, perhaps it's in an undesirable location, or maybe the rent is too high?)...