If you've got a digital radio for amateur radio use, you will already know about promiscuous mode and know what you are doing. 
If you are using a DMR radio as a scanner (understandable because the price of digital scanners is ridiculous and there may be nothing to listen to near you), you should make sure the radio you are buying has a digital monitor / digi mon mode, also known as promiscuous mode. With that mode turned on, it allows you to monitor a frequency and hear conversations regardless of slot, colour code or talkgroup. This is handy if you want to listen to all activity on a certain frequency or if you do not know what the correct settings should be.
If you tune into a DMR frequency and the radio doesn't have promiscuous mode turned on, and you do not have the correct colour codes, timeslot and, perhaps, talkgroup, you will hear nothing.
The AnyTone 878, which is a beautiful analogue and DMR radio, is an example of a DMR radio that has this feature and is great for learning more about amateur radio.
If you are using a DMR radio as a scanner (understandable because the price of digital scanners is ridiculous and there may be nothing to listen to near you), you should make sure the radio you are buying has a digital monitor / digi mon mode, also known as promiscuous mode. With that mode turned on, it allows you to monitor a frequency and hear conversations regardless of slot, colour code or talkgroup. This is handy if you want to listen to all activity on a certain frequency or if you do not know what the correct settings should be.
If you tune into a DMR frequency and the radio doesn't have promiscuous mode turned on, and you do not have the correct colour codes, timeslot and, perhaps, talkgroup, you will hear nothing.
The AnyTone 878, which is a beautiful analogue and DMR radio, is an example of a DMR radio that has this feature and is great for learning more about amateur radio.