If your V (apex at 90 degrees or so) is horizontal (parallel to the earth) then your effectively your creating a V beam by doing that... there will be gain (dBd) towards the direction of the legs of the V. At the apex there will be negative gain (dBd) which is now the rear of your beam.
This myth has been around for many years, but, just because you can find it repeated
on the internet doesn't mean it is correct.
If we build a 40m doublet and compare the forward gain between a straight version and
one with a 90 degree horizontal angle at the feedpoint, we get something like this:
40m: gain drops a bit over 1/2 dB when the antenna is bent. Antenna remains bidirectional.
20m: gain drops 2.7 dB when the antenna is bent. Antenna is nearly omnidirectional.
15m: gain increases 1.5dB when the antenna is bent. Front to back ratio is about 2dB.
10m: gain increases almost 2dB when the antenna is bent. F/B is about 1dB.
A vee beam requires wires at least 3/4 wavelength long, and typically 2 to 6 wavelengths
to get significant gain. The optimum angle depends on the wire length in wavelengths, and
can be narrower or wider than 90 degrees. The optimum vee angle for maximum gain on 15m
is about 130 degrees, while 90 is about right on 10m (1 wavelength legs) and narrow angles
for longer leg lengths.
Front to back ratio is rarely very high unless
the wires are terminated.
Conceptually this is how a Hex Beam works (the same principle but also very different)
Actually they have no relation to each other. The gain of a vee beam is achieved by
aligning the lobes that appear at angles along a long wire. A Hex beam or other yagi
uses parallel (though sometimes bent) half wave elements with parasitic coupling
among them to establish a phase shift that enhances the signal in one direction.
A yagi or Hex is capable of much higher F/B than a vee beam.
A proper vee beam can provide gain in the same direction over a reasonably wide
frequency range (even when the angle isn't optmum) So a single antenna could
be used on 20m through 10m. By contrast, a Hex beam or other yagi variant
works only when the parasitic elements are near the optimum length, usually
covering only a single ham band (though they can be built with separate sets of
elements for multiple bands). In fact, if you use a 2-element yagi and lower
the frequency by 10% or so, the antenna will reverse direction. That doesn't
happen with a vee beam.