The problem is that today many people are mostly used to PC's where most things just hook up to it with "standard cables". As a result there is a large contingent of users that hardly know even the names of the singals in a serial cable then yet understand the pin functions, pin numbering etc etc.

It is not like the old days of running CP/M on an S100 computer where every thing that you looked that had serial ports used different kinds of connectors, different pinouts, and different handshake protocols.
I can even remember the daisy wheel printers that used the RTS line to indicate a buffer full status in the printer.

A breakout box as suggested above is a great idea. You can do the best if you get one that has provision for an internal battery power supply. These have buffer chips on the RS232 lines so that the LEDs are not directly connected to the port pins of the port you are monitoring and thus not loading the signals.

I could suggest that you debug your 8052 embedded serial port while connected to a PC. This will give you a good amount of control on the PC side if you use a terminal emulator program. It is much easier to work out things if you can control what gets semt

Good Luck
Michel Karas