Signal services vary from honest to fraudulent, but they share a structural flaw. A copied entry arrives without the reasoning, the risk parameters, or the context, so the follower cannot manage the position when it does not behave as promised.
The economics deserve attention. A provider earning from subscriptions is paid for signals regardless of outcome, which is a different business from trading. Results are typically unaudited, losers vanish from the record, and slippage for a hundred followers entering at once is borne by the followers. Some groups exist mainly to provide exit-liquidity for the operator.
If you use one, treat it as a source of ideas subject to your own rules and size limits, log the results separately, and be honest after fifty trades about whether it added anything. See peer-review-group for the version that builds skill instead.
Related: copy-trading-psychology, exit-liquidity, shill, peer-review-group