When did this place go to the dogs and why can’t you lead a horse to water and make it drink?

We have all of
these phrases and meanings that we use every day about money, life and more,
but few of them do us really know or think about them in their reality of
usage.

For example, where
does a slush fund really come from; do
you ever sell yourself short; why is
something cheap at half the price; when
did this place go to the dogs; and how
come you can lead a horse to water but
can’t make it drink?

To find out, here
are a few answers with nearly all of them something to do with money, banking
and trade.

A slush fund is a hidden cache of money
used for illegal or corrupt political purpose. 
It’s origin is from the 19th century, when there was a practice onboard
ships of boiling up large pots of pork and other fatty meats. The fat that rose
to the top of the kettles was stored in vats and then sold to soap and candle
makers. The money received from the sale of the 'slush' was used for the crew's
comfort and entertainment.

If you sell yourself short, you probably have
not made the best of your virtues, e.g. don't sell yourself short, you are a good singer.  The phrase itself comes from the short
selling of stocks.  Selling a stock short
is a bet that the value of the stock is going down. Hence selling yourself short is an expectation that you are on the
decline.

People who make
money hand over fist are the fastest
at turning over the cash.  The phrase
dates back to the sailors on ancient ships climbing ropes and hoisting
sails.   The best seamen were those who could do this
action the fastest.  Therefore, the
phrase hand over fist appeared to
describe the one hand clenching a rope whilst the other deftly moves above it,
to suggest quickness and success.

The phrase cheap at half the price is not related
to price but to quality, as in saying that something is of very poor quality
could still be thought of as “cheap”, even if it were “half the price”. The
saying first came into usage in the mid-19th century, when some less than
frugal members of the aristocracy were forced to borrow money from high
interest charging money lenders.   The payday
lenders of 200 years ago if you like.  The
lenders were regarded as “cheap” individuals for so demeaning themselves by lending
money at such high rates of interest, that they would still be regarded as
“cheap” even if they charged half the rate.

A place has gone to the dogs if it has become
worthless, with phrase originating from Medieval times when the people eating
from the baronial tables would throw the worthless scraps of meat to the dogs
as they had no value as food anymore.

Finally, you can lead a horse to water but can’t make
it drink? first appeared in the 12th century, when horses were the main
form of transport.  At the end of a long
ride, a horse would need a drink but some would be so stubborn they would
refuse.  For centuries that truth has
been applied to people who do what they want to, even though you try to
persuade them otherwise.

Thanks to Jokes for these and a lot of other humorous insights.