As a Ham there is a lot about this that never gets understood or explained.
If you will try to understand, I will attempt to make some sense of it.
Your typical CB receiver performance:
1. Your receive is very broad banded, has very little selectivity to reject close by signals known a bleed over. Splatter and bleed over are not the same thing. Harmonics are different yet.
2 It has poor IMD response within the receiver. Often mistaken for bleed over
3. There is, in most cases, one filter in the intermediate stage.
4. Noise blanker operation can create IMD within the radio on top of all the rest.
Bottom line is a CB receiver has very little selectivity to begin with because it has it cover 40 channel frequencies without much attenuation. This is the low cost you pay for with these low performance radios.
In common terms it called being broad as a Barn Door.
This is a strike against you for interference rejection..
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Transmitter operation:
1. Over power operation generates signals too high in level and broad band widths for a CB receiver to handle..
2. If the transmitter is overdriven at any power level it generates inter modulation distortion products you hear as splatter over a wide frequency range.
Refer back to above. Your receiver cannot separate it out when it's on so wide a frequency spread. The best receivers cannot reject anything in it's band pass because it's RF signal the same as any desired signal but just happens to be undesirable..
3. Add to this, power mikes driving the radio into distortion which is also passed onto an amplifier so makes IMD totals worse yet.
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These are the basics of what you have to put up with when anyone abuses equipment and rules.
A. The radios were limited to a legal 5 watts.
B. No mods.
C. No amplifiers.
D. Channels with 10 kc spacing within 40 channels.
E. Antenna limits.
All for a reason.
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With all this being said, you should begin to understand why there are problems with people who violate the rules by the results you hear.
The FCC formulated the rules knowing what the results would be if left open to interpretation and unchecked.
Add to this un-enforcement and you have the recipe for discontent you hear and feel.
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Amateur radio license for that service is an agreement by the holder with the FCC to abide by the Part 97 rules set forth for that service. Not everyone does but most do to a high degree.
I might add that Ham radio is the only radio hobby besides the military to allow continuously variable frequency control within their allowed band limits.
There are people in any hobby involving others, that will try to get away with anything just because they can and always look for attention by doing so..
It often falls under the heading of ignorance and/or some deficiency in the way they want to relate to others in a disrespectful manner.
Those who break the rules and show no respect make others pay for it.
I hope this perspective has some value.
Thanks for reading.
Good luck.