Does seem alpha quadrant sensors tend to be easily fooled. Peak Performance has been mentioned a few times here, and for good reason.
DATA says in the ep
"I have several examples of Commander Riker's battle technique. At the Academy, he calculated a sensory blind spot on a Tholian vessel and hid within it during a battle simulation. And as a lieutenant aboard the Potemkin, his solution
to a crisis was to shut down all power, and hang over a planet's
magnetic pole, thus confusing his opponent's sensors."
Worf was also not only able to spoof the Enterprise's sensors which create the visual image of a romulan ship on the view screen.. but are also able to pull the same trick on the Ferengi.
Worf was able to do that because he "had knowledge of the Enterprise's
security system" —in other words, he knew the backdoor to exploit to fool the Enterprise's
computers. The situation with the Kreecta
is less certain, and may have been a case in which the Hathaway
had looped back after its seeming destruction, and the Ferengi assuming that it was another Federation starship on an attack vector.
Also, how many times in star trek have you heard them talking about mimicking some other species warp signature or masking their own signature or even masking their warp trail entirely.
I do not recall any instance of warp-signature mimickry. We have seen that the Romulans learned to mask their engine emissions to further hide their ships while cloaked. But in "Tin Man", the Enterprise
was able to pick up trace readings of a cloaked Warbird
which was running at maximum warp and causing its emissions to leak out past the stealthmasking and the cloaking field.
Can't help but remember the Enterprise A flying what was prolly rather deep into Klingon territory to rescue Kirk and McCoy in which the Klingons had detected the Ent, but where completely incapable of identifying the fact it was not of Klingon origin.
It could be the case that, in that time period, the sensor suites of Klingon monitor stations only had the capacity to read raw contact data but had no transponder-ID or distant identification capability; hence the necessity of opening contact to demand the ship's identity.