As it happens I've just been updating my list of issues that affect
underwriting in Chicago and Suburbs, based on conversations with local
agents. The most common issues a

Roofs obviously near end of their useful lives.

Porches or stairs with missing or damaged railings.

Coverage of large areas with ivy or other similar plants (for example,
State Farm).

EIFS or Dryvit synthetic stucco over *frame* construction.

Frame buildings in close proximity to another structure (especially a
problem in Chicago).

Any fused (as oposed to circuit breaker) based systems, even if 100A in
good conditon.

Knob and Tube wiring

For some companies, *any* electrical service less than 100A (or
example, Hartford).

Generally, for pre-1900 construction some companies (for example,
Hartford) expect to see major updating of systems such as electrical
and HVAC.

If an applicant states that there has been recent updating some
companies (for example, Allstate) may request to review receipts for
the repairs, and expect that these will be from a "licensed
contractor".

Previous claims or inquiries discovered during a CLUE search,
especially for water damage.