Sparkfun RS232 Shifter SMD TTL Waveform DC Offset
The level shifter with transistors and negative voltage scavenging is a valid though sometimes finicky set-up.  

It will not give correct voltages if you do not have the RS-IN pin connected to a negative voltage (usually supplied by the RS-232 driven output when in idle mode and stored with the capacitor when transmitting from the RS-232 side) when measuring the level shifted output.  

If there is no pull down voltage available it will offer some pretty weak low voltage.

I suggest you test the voltages with static signals and measure the voltage on the capacitor to see that it is getting charged to a negative voltage.  Also check that you have valid ground connections on both sides (and your scope :-) ).

Your scope sampling points seem to be drifting in the screen shots, not sure if the decoding will be correct but it is trying.

If it is possible I would try to use 5V IO on the TTL side as the circuit will drop at least one Vce on the positive swing on the RS-232 side. With 3.3 the output is only just within the +-3V limits.  However if your 3.3V TTL output does not reach a 5V VCC rail you may find that it does not turn off the transistor and you will not see a good negative voltage on the RS-OUT pin.