On 2008-02-22 20:24:47 -0800, WingFlaps said:

Hi all,
A recurring theme seems to be that one should should not rely in fuel
gauges. I can understand that from a safety point of view (I always
dip the tank before start), but I get the feeling that they are
considered just plain inaccurate.

If an airplane does not have accurate fuel gauges then it is not
airworthy. Knowingly climbing into an aircraft that you know has
inaccurate fuel gauges is both dangerous and illegal. That is why you
check them during preflight. From FAR 91.205:

(a) General. Except as provided in paragraphs (c)(3) and (e) of this
section, no person may operate a powered civil aircraft with a standard
category U.S. airworthiness certificate in any operation described in
paragraphs (b) through (f) of this section unless that aircraft
contains the instruments and equipment specified in those paragraphs
(or FAA-approved equivalents) for that type of operation, and those
instruments and items of equipment are in operable condition.
(b) Visual-flight rules (day). For VFR flight during the day, the
following instruments and equipment are required:
(1) Airspeed indicator.
....
(9) Fuel gauge indicating the quantity of fuel in each tank.
--
Waddling Eagle
World Famous Flight Instructor